diff --git a/rest_framework-stubs/routers.pyi b/rest_framework-stubs/routers.pyi
index 41c2bbb72..1301b6763 100644
--- a/rest_framework-stubs/routers.pyi
+++ b/rest_framework-stubs/routers.pyi
@@ -35,6 +35,7 @@ class BaseRouter(metaclass=RenameRouterMethods):
     def register(
         self, prefix: str, viewset: type[ViewSetMixin], basename: str | None = ..., base_name: str | None = ...
     ) -> None: ...
+    def is_already_registered(self, new_basename: str) -> bool: ...
     def get_default_basename(self, viewset: type[ViewSetMixin]) -> str: ...
     def get_urls(self) -> list[_AnyURL]: ...
     @property
diff --git a/scripts/stubtest/allowlist_todo.txt b/scripts/stubtest/allowlist_todo.txt
index 5ce812434..dc065201a 100644
--- a/scripts/stubtest/allowlist_todo.txt
+++ b/scripts/stubtest/allowlist_todo.txt
@@ -142,7 +142,6 @@ rest_framework.filters.search_smart_split
 rest_framework.generics.GenericAPIView.__class_getitem__
 rest_framework.request.Request.__class_getitem__
 rest_framework.response.Response.__class_getitem__
-rest_framework.routers.BaseRouter.is_already_registered
 rest_framework.serializers.Field.__class_getitem__
 rest_framework.serializers.ListSerializer.run_child_validation
 rest_framework.serializers.ModelSerializer.get_unique_together_constraints