diff --git a/amber/src/main/python/core/architecture/packaging/output_manager.py b/amber/src/main/python/core/architecture/packaging/output_manager.py
index bc6829520eb..5053fd01f49 100644
--- a/amber/src/main/python/core/architecture/packaging/output_manager.py
+++ b/amber/src/main/python/core/architecture/packaging/output_manager.py
@@ -124,11 +124,10 @@ def add_output_port(
         if port_id.internal is None:
             port_id.internal = False
 
-        if storage_uri_base is not None:
-            self.set_up_port_storage_writer(port_id, storage_uri_base)
-
         # each port can only be added and initialized once.
         if port_id not in self._ports:
+            if storage_uri_base is not None:
+                self.set_up_port_storage_writer(port_id, storage_uri_base)
             self._ports[port_id] = WorkerPort(schema)
 
     def set_up_port_storage_writer(self, port_id: PortIdentity, storage_uri_base: str):
diff --git a/amber/src/test/python/core/architecture/packaging/test_output_manager.py b/amber/src/test/python/core/architecture/packaging/test_output_manager.py
index d929dda62b7..841e122be67 100644
--- a/amber/src/test/python/core/architecture/packaging/test_output_manager.py
+++ b/amber/src/test/python/core/architecture/packaging/test_output_manager.py
@@ -396,6 +396,17 @@ def test_port_can_only_be_added_once(self, output_manager):
         assert output_manager.get_port_ids() == [port_id]
         assert output_manager.get_port().get_schema() is schema_first
 
+    def test_duplicate_port_does_not_start_replacement_storage_writers(
+        self, output_manager
+    ):
+        output_manager.set_up_port_storage_writer = MagicMock()
+        port_id = PortIdentity(id=0, internal=False)
+        output_manager.add_output_port(port_id, MagicMock(), "vfs:///first")
+        output_manager.add_output_port(port_id, MagicMock(), "vfs:///duplicate")
+        output_manager.set_up_port_storage_writer.assert_called_once_with(
+            port_id, "vfs:///first"
+        )
+
     def test_sets_up_storage_writer_only_when_uri_given(self, output_manager):
         output_manager.set_up_port_storage_writer = MagicMock()
         port_a = PortIdentity(id=0, internal=False)