diff --git a/libs/core/tests/unit_tests/callbacks/test_sync_callback_manager.py b/libs/core/tests/unit_tests/callbacks/test_sync_callback_manager.py
index d8b3aab6001..44076c8460a 100644
--- a/libs/core/tests/unit_tests/callbacks/test_sync_callback_manager.py
+++ b/libs/core/tests/unit_tests/callbacks/test_sync_callback_manager.py
@@ -13,3 +13,24 @@ def test_remove_handler() -> None:
     manager = BaseCallbackManager([handler1], inheritable_handlers=[handler2])
     manager.remove_handler(handler1)
     manager.remove_handler(handler2)
+
+
+def test_merge_preserves_handler_distinction() -> None:
+    """Test that merging managers preserves the distinction between handlers.
+
+    This test verifies the correct behavior of the BaseCallbackManager.merge()
+    method. When two managers are merged, their handlers and
+    inheritable_handlers should be combined independently.
+    """
+    h1 = BaseCallbackHandler()
+    h2 = BaseCallbackHandler()
+    ih1 = BaseCallbackHandler()
+    ih2 = BaseCallbackHandler()
+
+    m1 = BaseCallbackManager(handlers=[h1], inheritable_handlers=[ih1])
+    m2 = BaseCallbackManager(handlers=[h2], inheritable_handlers=[ih2])
+
+    merged = m1.merge(m2)
+
+    assert set(merged.handlers) == {h1, h2}
+    assert set(merged.inheritable_handlers) == {ih1, ih2}