diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index 81d32323a..96af16937 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -31,7 +31,7 @@ jobs:
     strategy:
       matrix:
         visual_studio_arm64:
-          vmImage: "windows-2022"
+          vmImage: "windows-2025"
           cli11.std: 17
           cli11.build_type: Debug
           cli11.options: -G "Visual Studio 17 2022" -A ARM64
@@ -66,21 +66,21 @@ jobs:
           cli11.std: 14
           cli11.precompile: ON
         Windows17:
-          vmImage: "windows-2019"
+          vmImage: "windows-2022"
           cli11.std: 17
         Windows17PC:
-          vmImage: "windows-2019"
+          vmImage: "windows-2022"
           cli11.std: 17
           cli11.precompile: ON
         Windows11:
-          vmImage: "windows-2019"
+          vmImage: "windows-2022"
           cli11.std: 11
         Windows20:
-          vmImage: "windows-2022"
+          vmImage: "windows-2025"
           cli11.std: 20
           cli11.options: -DCMAKE_CXX_FLAGS="/EHsc"
         WindowsLatest:
-          vmImage: "windows-2022"
+          vmImage: "windows-2025"
           cli11.std: 23
           cli11.options: -DCMAKE_CXX_FLAGS="/EHsc"
         Linux17nortti:
diff --git a/include/CLI/impl/App_inl.hpp b/include/CLI/impl/App_inl.hpp
index cd382a6fd..80ff4c171 100644
--- a/include/CLI/impl/App_inl.hpp
+++ b/include/CLI/impl/App_inl.hpp
@@ -206,6 +206,12 @@ CLI11_INLINE Option *App::add_option(std::string option_name,
             if(op != nullptr && op->get_configurable()) {
                 throw(OptionAlreadyAdded("added option matches existing option: --" + ln));
             }
+            if(ln.size() == 1 || top_level_parent->get_allow_non_standard_option_names()) {
+                op = top_level_parent->get_option_no_throw("-" + ln);
+                if(op != nullptr && op->get_configurable()) {
+                    throw(OptionAlreadyAdded("added option matches existing option: -" + ln));
+                }
+            }
         }
         for(auto &sn : myopt.snames_) {
             const auto *op = top_level_parent->get_option_no_throw(sn);
@@ -216,6 +222,10 @@ CLI11_INLINE Option *App::add_option(std::string option_name,
             if(op != nullptr && op->get_configurable()) {
                 throw(OptionAlreadyAdded("added option matches existing option: -" + sn));
             }
+            op = top_level_parent->get_option_no_throw("--" + sn);
+            if(op != nullptr && op->get_configurable()) {
+                throw(OptionAlreadyAdded("added option matches existing option: --" + sn));
+            }
         }
     }
     if(allow_non_standard_options_ && !myopt.snames_.empty()) {
diff --git a/tests/OptionTypeTest.cpp b/tests/OptionTypeTest.cpp
index 346c3ac32..8ea57262d 100644
--- a/tests/OptionTypeTest.cpp
+++ b/tests/OptionTypeTest.cpp
@@ -951,6 +951,12 @@ TEST_CASE_METHOD(TApp, "vectorEmptyArg", "[optiontype]") {
     run();
     CHECK(cv.size() == 2);
     CHECK(cv[1] == "[]");
+
+    args = {"-c", "test1", "[[aa]]"};
+
+    run();
+    CHECK(cv.size() == 2);
+    CHECK(cv[1] == "[a]");
 }
 
 TEST_CASE_METHOD(TApp, "vectorDoubleArg", "[optiontype]") {
diff --git a/tests/SubcommandTest.cpp b/tests/SubcommandTest.cpp
index 337750d8b..4b1bd0f6d 100644
--- a/tests/SubcommandTest.cpp
+++ b/tests/SubcommandTest.cpp
@@ -1851,6 +1851,25 @@ TEST_CASE_METHOD(TApp, "subcommand_help", "[subcom]") {
     CHECK(called);
 }
 
+TEST_CASE_METHOD(TApp, "DuplicateErrors", "[subcom]") {
+    app.allow_non_standard_option_names();
+    app.add_option("-t");
+    app.add_option("m");
+    app.add_option("--quit");
+    auto *sub1 = app.add_option_group("sub1");
+
+    CHECK_THROWS_AS(sub1->add_option("-t"), CLI::OptionAlreadyAdded);
+    CHECK_THROWS_AS(sub1->add_option("--t"), CLI::OptionAlreadyAdded);
+    CHECK_THROWS_AS(sub1->add_option("t"), CLI::OptionAlreadyAdded);
+    CHECK_THROWS_AS(sub1->add_option("-m"), CLI::OptionAlreadyAdded);
+    CHECK_THROWS_AS(sub1->add_option("--m"), CLI::OptionAlreadyAdded);
+    CHECK_THROWS_AS(sub1->add_option("m"), CLI::OptionAlreadyAdded);
+    CHECK_THROWS_AS(sub1->add_option("quit"), CLI::OptionAlreadyAdded);
+    CHECK_THROWS_AS(sub1->add_option("--quit"), CLI::OptionAlreadyAdded);
+    sub1->allow_non_standard_option_names();
+    CHECK_THROWS_AS(sub1->add_option("-quit"), CLI::OptionAlreadyAdded);
+}
+
 TEST_CASE_METHOD(TApp, "AliasErrors", "[subcom]") {
     auto *sub1 = app.add_subcommand("sub1");
     auto *sub2 = app.add_subcommand("sub2");