Allow existing configs to be registered (#24760)

src/transformers/models/auto/auto_factory.py

@@ -418,7 +418,7 @@ class _BaseAutoModelClass:
             else:
                 repo_id = config.name_or_path
             model_class = get_class_from_dynamic_module(class_ref, repo_id, **kwargs)
-            cls._model_mapping.register(config.__class__, model_class)
+            cls._model_mapping.register(config.__class__, model_class, exist_ok=True)
             _ = kwargs.pop("code_revision", None)
             return model_class._from_config(config, **kwargs)
         elif type(config) in cls._model_mapping.keys():
@@ -477,7 +477,7 @@ class _BaseAutoModelClass:
                 class_ref, pretrained_model_name_or_path, **hub_kwargs, **kwargs
             )
             _ = hub_kwargs.pop("code_revision", None)
-            cls._model_mapping.register(config.__class__, model_class)
+            cls._model_mapping.register(config.__class__, model_class, exist_ok=True)
             return model_class.from_pretrained(
                 pretrained_model_name_or_path, *model_args, config=config, **hub_kwargs, **kwargs
             )
@@ -492,7 +492,7 @@ class _BaseAutoModelClass:
         )
 
     @classmethod
-    def register(cls, config_class, model_class):
+    def register(cls, config_class, model_class, exist_ok=False):
         """
         Register a new model for this class.
 
@@ -508,7 +508,7 @@ class _BaseAutoModelClass:
                 f"config class you passed (model has {model_class.config_class} and you passed {config_class}. Fix "
                 "one of those so they match!"
             )
-        cls._model_mapping.register(config_class, model_class)
+        cls._model_mapping.register(config_class, model_class, exist_ok=exist_ok)
 
 
 class _BaseAutoBackboneClass(_BaseAutoModelClass):
@@ -719,13 +719,13 @@ class _LazyAutoMapping(OrderedDict):
         model_type = self._reverse_config_mapping[item.__name__]
         return model_type in self._model_mapping
 
-    def register(self, key, value):
+    def register(self, key, value, exist_ok=False):
         """
         Register a new model in this mapping.
         """
         if hasattr(key, "__name__") and key.__name__ in self._reverse_config_mapping:
             model_type = self._reverse_config_mapping[key.__name__]
-            if model_type in self._model_mapping.keys():
+            if model_type in self._model_mapping.keys() and not exist_ok:
                 raise ValueError(f"'{key}' is already used by a Transformers model.")
 
         self._extra_content[key] = value