diff --git a/docs/rules.rst b/docs/rules.rst
index 15416bf3d..9fdb39911 100644
--- a/docs/rules.rst
+++ b/docs/rules.rst
@@ -14,10 +14,10 @@ This page describes the rules and their options.
    :local:
    :depth: 1
 
-anchor-duplicates
-------
+anchors
+-------
 
-.. automodule:: yamllint.rules.anchor_duplicates
+.. automodule:: yamllint.rules.anchors
 
 braces
 ------
@@ -123,8 +123,3 @@ truthy
 ---------------
 
 .. automodule:: yamllint.rules.truthy
-
-unknown-aliases
----------------
-
-.. automodule:: yamllint.rules.unknown_aliases
diff --git a/tests/rules/test_anchor_duplicates.py b/tests/rules/test_anchor_duplicates.py
deleted file mode 100644
index d21367396..000000000
--- a/tests/rules/test_anchor_duplicates.py
+++ /dev/null
@@ -1,44 +0,0 @@
-# Copyright (C) 2021 Sergei Mikhailov
-#
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-from tests.common import RuleTestCase
-
-
-NORMAL_ANCHOR = '''---
-key: &keyanchor a
-otherkey: *keyanchor
-'''
-
-DUPLICATED_ANCHOR = '''---
-key1: &keyanchor a
-key2: &keyanchor b
-otherkey: *keyanchor
-'''
-
-
-class AnchorDuplicatesTestCase(RuleTestCase):
-    rule_id = 'anchor-duplicates'
-
-    def test_disabled(self):
-        conf = 'anchor-duplicates: disable'
-
-        self.check(NORMAL_ANCHOR, conf)
-        self.check(DUPLICATED_ANCHOR, conf)
-
-    def test_enabled(self):
-        conf = 'anchor-duplicates: enable'
-
-        self.check(NORMAL_ANCHOR, conf)
-        self.check(DUPLICATED_ANCHOR, conf, problem=(3,7))
diff --git a/tests/rules/test_unknown_aliases.py b/tests/rules/test_anchors.py
similarity index 50%
rename from tests/rules/test_unknown_aliases.py
rename to tests/rules/test_anchors.py
index eee9964b3..7af9d9c52 100644
--- a/tests/rules/test_unknown_aliases.py
+++ b/tests/rules/test_anchors.py
@@ -16,6 +16,22 @@
 from tests.common import RuleTestCase
 
 
+NORMAL_ANCHOR = '''---
+key: &keyanchor a
+otherkey: *keyanchor
+'''
+
+NORMAL_ANCHOR_NO_DOC_START = '''---
+key: &keyanchor a
+otherkey: *keyanchor
+'''
+
+DUPLICATED_ANCHOR = '''---
+key1: &keyanchor a
+key2: &keyanchor b
+otherkey: *keyanchor
+'''
+
 HIT_ANCHOR_POINTER = '''---
 key: &keyanchor a
 otherkey: *keyanchor
@@ -67,33 +83,83 @@
 '''
 
 
-class UnknownAliasesTestCase(RuleTestCase):
-    rule_id = 'unknown-aliases'
+
+DEFAULT = {'forbid-unknown-aliases': True,
+           'forbid-duplicated-anchors': False}
+
+
+class AnchorsTestCase(RuleTestCase):
+    rule_id = 'anchors'
 
     def test_disabled(self):
-        conf = 'unknown-aliases: disable'
+        conf = ('anchors:\n'
+                '  forbid-unknown-aliases: false\n'
+                '  forbid-duplicated-anchors: false\n'
+        )
 
+        self.check(NORMAL_ANCHOR, conf)
+        self.check(NORMAL_ANCHOR_NO_DOC_START, conf)
+        self.check(DUPLICATED_ANCHOR, conf)
         self.check(HIT_ANCHOR_POINTER, conf)
+        self.check(MISS_ANCHOR_POINTER, conf)
         self.check(HIT_ANCHOR_MERGE, conf)
+        self.check(MISS_ANCHOR_MERGE, conf)
         self.check(MULTI_HIT_ANCHOR_POINTER, conf)
+        self.check(MULTI_MISS_ANCHOR_POINTER, conf)
         self.check(MULTI_DOC_HIT_ANCHOR_POINTER, conf)
+        self.check(MULTI_DOC_MISS_ANCHOR_POINTER, conf)
 
+    def test_unknown_aliases(self):
+        conf = ('anchors:\n'
+                '  forbid-unknown-aliases: true\n'
+                '  forbid-duplicated-anchors: false\n'
+        )
+
+        self.check(NORMAL_ANCHOR, conf)
+        self.check(DUPLICATED_ANCHOR, conf)
+        self.check(HIT_ANCHOR_POINTER, conf)
+        self.check(MISS_ANCHOR_POINTER, conf, problem=(3, 11))
+        self.check(HIT_ANCHOR_MERGE, conf)
+        self.check(MISS_ANCHOR_MERGE, conf, problem=(5, 7))
+        self.check(MULTI_HIT_ANCHOR_POINTER, conf)
+        self.check(MULTI_MISS_ANCHOR_POINTER, conf,
+                   problem1=(3, 11), problem2=(4, 16))
+        self.check(MULTI_DOC_HIT_ANCHOR_POINTER, conf)
+        self.check(MULTI_DOC_MISS_ANCHOR_POINTER, conf,
+                   problem1=(3, 11), problem2=(6, 11))
+
+    def test_duplicated_anchors(self):
+        conf = ('anchors:\n'
+                '  forbid-unknown-aliases: false\n'
+                '  forbid-duplicated-anchors: true\n'
+        )
+
+        self.check(NORMAL_ANCHOR, conf)
+        self.check(DUPLICATED_ANCHOR, conf, problem=(3, 7))
+        self.check(HIT_ANCHOR_POINTER, conf)
         self.check(MISS_ANCHOR_POINTER, conf)
+        self.check(HIT_ANCHOR_MERGE, conf)
         self.check(MISS_ANCHOR_MERGE, conf)
+        self.check(MULTI_HIT_ANCHOR_POINTER, conf)
         self.check(MULTI_MISS_ANCHOR_POINTER, conf)
+        self.check(MULTI_DOC_HIT_ANCHOR_POINTER, conf)
         self.check(MULTI_DOC_MISS_ANCHOR_POINTER, conf)
 
     def test_enabled(self):
-        conf = 'unknown-aliases: enable'
+        conf = ('anchors:\n'
+                '  forbid-unknown-aliases: true\n'
+                '  forbid-duplicated-anchors: true\n'
+        )
 
+        self.check(NORMAL_ANCHOR, conf)
+        self.check(DUPLICATED_ANCHOR, conf, problem=(3, 7))
         self.check(HIT_ANCHOR_POINTER, conf)
+        self.check(MISS_ANCHOR_POINTER, conf, problem=(3, 11))
         self.check(HIT_ANCHOR_MERGE, conf)
-        self.check(MULTI_HIT_ANCHOR_POINTER, conf)
-        self.check(MULTI_DOC_HIT_ANCHOR_POINTER, conf)
-
-        self.check(MISS_ANCHOR_POINTER, conf, problem=(3,11))
         self.check(MISS_ANCHOR_MERGE, conf, problem=(5, 7))
+        self.check(MULTI_HIT_ANCHOR_POINTER, conf)
         self.check(MULTI_MISS_ANCHOR_POINTER, conf,
                    problem1=(3, 11), problem2=(4, 16))
+        self.check(MULTI_DOC_HIT_ANCHOR_POINTER, conf)
         self.check(MULTI_DOC_MISS_ANCHOR_POINTER, conf,
                    problem1=(3, 11), problem2=(6, 11))
diff --git a/yamllint/conf/default.yaml b/yamllint/conf/default.yaml
index 021160496..597acbdaa 100644
--- a/yamllint/conf/default.yaml
+++ b/yamllint/conf/default.yaml
@@ -6,7 +6,7 @@ yaml-files:
   - '.yamllint'
 
 rules:
-  anchor-duplicates: disable
+  anchors: enable
   braces: enable
   brackets: enable
   colons: enable
@@ -32,4 +32,3 @@ rules:
   trailing-spaces: enable
   truthy:
     level: warning
-  unknown-aliases: enable
diff --git a/yamllint/rules/__init__.py b/yamllint/rules/__init__.py
index 8d18f8a7b..f33d699c5 100644
--- a/yamllint/rules/__init__.py
+++ b/yamllint/rules/__init__.py
@@ -15,7 +15,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 from yamllint.rules import (
-    anchor_duplicates,
+    anchors,
     braces,
     brackets,
     colons,
@@ -37,11 +37,10 @@
     quoted_strings,
     trailing_spaces,
     truthy,
-    unknown_aliases,
 )
 
 _RULES = {
-    anchor_duplicates.ID: anchor_duplicates,
+    anchors.ID: anchors,
     braces.ID: braces,
     brackets.ID: brackets,
     colons.ID: colons,
@@ -63,7 +62,6 @@
     quoted_strings.ID: quoted_strings,
     trailing_spaces.ID: trailing_spaces,
     truthy.ID: truthy,
-    unknown_aliases.ID: unknown_aliases,
 }
 
 
diff --git a/yamllint/rules/anchor_duplicates.py b/yamllint/rules/anchor_duplicates.py
deleted file mode 100644
index cb0d9e878..000000000
--- a/yamllint/rules/anchor_duplicates.py
+++ /dev/null
@@ -1,65 +0,0 @@
-# Copyright (C) 2021 Sergei Mikhailov
-#
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-"""
-Use this rule to forbid duplicated anchors.
-
-.. rubric:: Examples
-
-#. With ``anchor-duplicates: {}``
-
-   the following code snippet would **PASS**:
-   ::
-
-    clients:
-        jack: &jack_client
-            billing_id: 1234
-        bill: &bill_client
-            billing_id: 5678
-    target_client: *jack_client
-
-   the following code snippet would **FAIL**:
-   ::
-
-    clients:
-        jack: &jack_client
-            billing_id: 1234
-        bill: &jack_client
-            billing_id: 5678
-    target_client: *jack_client
-"""
-
-from yaml import DocumentStartToken, AnchorToken, AliasToken
-
-from yamllint.linter import LintProblem
-
-
-ID = 'anchor-duplicates'
-TYPE = 'token'
-
-CONF = {'anchor-duplicates': bool}
-DEFAULT = {'anchor-duplicates': True}
-
-def check(conf, token, __prev, __next, __nextnext, context):
-    if conf['anchor-duplicates']:
-        if isinstance(token, DocumentStartToken):
-            context['anchors'] = []
-        elif 'anchors' in context:
-            if isinstance(token, AnchorToken):
-                if token.value in context['anchors']:
-                    yield LintProblem(
-                        token.start_mark.line + 1, token.start_mark.column + 1,
-                        f'duplicated anchor "{token.value}"')
-                context['anchors'].append(token.value)
diff --git a/yamllint/rules/anchors.py b/yamllint/rules/anchors.py
new file mode 100644
index 000000000..275b61599
--- /dev/null
+++ b/yamllint/rules/anchors.py
@@ -0,0 +1,124 @@
+# Copyright (C) 2021 Sergei Mikhailov
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+"""
+Use this rule to prevent duplicated anchors and referencing to non-existent anchors.
+
+.. rubric:: Options
+
+* Use ``forbid-unknown-aliases`` to prevent referencing to anchors before assigment or referencing to non-existent anchors.
+* Use ``forbid-duplicated-anchors`` to prevent duplicated anchors.
+
+
+.. rubric:: Examples
+
+#. With ``anchors: {forbid-duplicated-anchors: true}``
+
+   the following code snippet would **PASS**:
+   ::
+
+    clients:
+        jack: &jack_client
+            billing_id: 1234
+        bill: &bill_client
+            billing_id: 5678
+    target_client: *jack_client
+
+   the following code snippet would **FAIL**:
+   ::
+
+    clients:
+        jack: &jack_client
+            billing_id: 1234
+        bill: &jack_client
+            billing_id: 5678
+    target_client: *jack_client
+
+#. With ``anchors: {forbid-unknown-aliases: true}``
+
+   the following code snippet would **PASS**:
+   ::
+
+    address: &address |
+      Williams St. 13
+    target_address: *address
+
+   the following code snippet would **PASS**:
+   ::
+
+    default_address: &address
+      state: South Carolina
+      city:  Barnwell
+    target_address:
+      <<: *address
+      city: Barnaul
+
+   the following code snippet would **FAIL**:
+   ::
+
+    address: &address |
+      Williams St. 13
+    target_address: *wrong_address
+
+
+   the following code snippet would **FAIL**:
+   ::
+
+    default_address: &address
+      state: South Carolina
+      city:  Barnwell
+    target_address:
+      <<: *wrong_address
+      city: Barnaul
+"""
+
+
+from yaml import StreamStartToken, DocumentStartToken, AnchorToken, AliasToken
+
+from yamllint.linter import LintProblem
+
+
+ID = 'anchors'
+TYPE = 'token'
+
+CONF = {'forbid-unknown-aliases': bool,
+        'forbid-duplicated-anchors': bool}
+DEFAULT = {'forbid-unknown-aliases': True,
+           'forbid-duplicated-anchors': False}
+
+
+def check(conf, token, prev, next, nextnext, context):
+    if conf['forbid-unknown-aliases'] or conf['forbid-duplicated-anchors']:
+        # In case of DocumentStartToken `---` is missing
+        if isinstance(token, StreamStartToken):
+            context['anchors'] = []
+        if isinstance(token, DocumentStartToken):
+            context['anchors'] = []
+        elif isinstance(token, AnchorToken):
+            context['anchors'].append(token.value)
+
+    if conf['forbid-unknown-aliases'] and isinstance(token, AliasToken):
+        if token.value not in context['anchors']:
+            yield LintProblem(
+                token.start_mark.line + 1, token.start_mark.column + 1,
+                f'anchor "{token.value}" is used before assignment')
+
+
+    if conf['forbid-duplicated-anchors'] and isinstance(token, AnchorToken):
+        anchors_count = context['anchors'].count(token.value)
+        if anchors_count == 2:
+            yield LintProblem(
+                token.start_mark.line + 1, token.start_mark.column + 1,
+                f'duplicated anchor "{token.value}')
diff --git a/yamllint/rules/unknown_aliases.py b/yamllint/rules/unknown_aliases.py
deleted file mode 100644
index b4264f8ba..000000000
--- a/yamllint/rules/unknown_aliases.py
+++ /dev/null
@@ -1,82 +0,0 @@
-# Copyright (C) 2021 Sergei Mikhailov
-#
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-"""
-Use this rule to prevent aliases pointing to pointers that don't exist.
-
-.. rubric:: Examples
-
-#. With ``unknown-aliases: {}``
-
-   the following code snippet would **PASS**:
-   ::
-
-    address: &address |
-      Williams St. 13
-    target_address: *address
-
-   the following code snippet would **PASS**:
-   ::
-
-    default_address: &address
-      state: South Carolina
-      city:  Barnwell
-    target_address:
-      <<: *address
-      city: Barnaul
-
-   the following code snippet would **FAIL**:
-   ::
-
-    address: &address |
-      Williams St. 13
-    target_address: *wrong_address
-
-
-   the following code snippet would **FAIL**:
-   ::
-
-    default_address: &address
-      state: South Carolina
-      city:  Barnwell
-    target_address:
-      <<: *wrong_address
-      city: Barnaul
-"""
-
-from yaml import DocumentStartToken, AnchorToken, AliasToken
-
-from yamllint.linter import LintProblem
-
-
-ID = 'unknown-aliases'
-TYPE = 'token'
-
-CONF = {'unknown-aliases': bool}
-DEFAULT = {'unknown-aliases': True}
-
-
-def check(conf, token, __prev, __next, __nextnext, context):
-    if conf['unknown-aliases']:
-        if isinstance(token, DocumentStartToken):
-            context['anchors'] = []
-        elif 'anchors' in context:
-            if isinstance(token, AnchorToken):
-                context['anchors'].append(token.value)
-            elif isinstance(token, AliasToken):
-                if token.value not in context['anchors']:
-                    yield LintProblem(
-                        token.start_mark.line + 1, token.start_mark.column + 1,
-                        f'anchor "{token.value}" is used before assignment')