diff --git a/src/openai/_event_handler.py b/src/openai/_event_handler.py
index bbcbd22a6b..c141bdcef3 100644
--- a/src/openai/_event_handler.py
+++ b/src/openai/_event_handler.py
@@ -42,7 +42,7 @@ def remove(self, event_type: str, handler: EventHandler) -> None:
             handlers = self._handlers.get(event_type)
             if handlers is not None:
                 for index, registration in enumerate(handlers):
-                    if registration.handler == handler:
+                    if registration.handler is handler or registration.handler == handler:
                         del handlers[index]
                         break
         finally:
diff --git a/tests/test_event_handler.py b/tests/test_event_handler.py
new file mode 100644
index 0000000000..fc71e31f61
--- /dev/null
+++ b/tests/test_event_handler.py
@@ -0,0 +1,65 @@
+from __future__ import annotations
+
+from openai._event_handler import EventHandlerRegistry
+
+
+def test_once_registration_is_scoped_to_its_event() -> None:
+    def handler(_event: object) -> None:
+        pass
+
+    registry = EventHandlerRegistry()
+    registry.add("persistent", handler)
+    registry.add("one-shot", handler, once=True)
+
+    assert registry.get_handlers("persistent") == [handler]
+    assert registry.get_handlers("persistent") == [handler]
+    assert registry.get_handlers("one-shot") == [handler]
+    assert registry.get_handlers("one-shot") == []
+
+
+def test_remove_only_removes_the_first_matching_registration() -> None:
+    def handler(_event: object) -> None:
+        pass
+
+    registry = EventHandlerRegistry()
+    registry.add("event", handler)
+    registry.add("event", handler, once=True)
+
+    registry.remove("event", handler)
+
+    assert registry.get_handlers("event") == [handler]
+    assert registry.get_handlers("event") == []
+
+
+def test_remove_prefers_identity_to_overloaded_equality() -> None:
+    class Handler:
+        def __call__(self, _event: object) -> None:
+            pass
+
+        def __eq__(self, other: object) -> bool:
+            del other
+            raise AssertionError("identity matches must not invoke __eq__")
+
+    handler = Handler()
+    registry = EventHandlerRegistry()
+    registry.add("event", handler)
+
+    registry.remove("event", handler)
+
+    assert registry.has_handlers("event") is False
+
+
+def test_merge_preserves_each_registration_mode() -> None:
+    def handler(_event: object) -> None:
+        pass
+
+    source = EventHandlerRegistry()
+    target = EventHandlerRegistry()
+    source.add("event", handler)
+    source.add("event", handler, once=True)
+
+    source.merge_into(target)
+
+    assert source.has_handlers("event") is False
+    assert target.get_handlers("event") == [handler, handler]
+    assert target.get_handlers("event") == [handler]