fix tie_word_embeddings

Author: DesmonDay

paddlenlp/trainer/plugins/unified_checkpoint.py

@@ -1034,7 +1034,11 @@ def get_expected_state_dict(model_to_save):
     elif isinstance(model_to_save, PrefixModelForCausalLM):
         state_dict = model_to_save.prefix_encoder.state_dict()
 
-    if hasattr(model_to_save, "_tied_weights_keys") and model_to_save._tied_weights_keys is not None:
+    if (
+        model_to_save.config.tie_word_embeddings
+        and hasattr(model_to_save, "_tied_weights_keys")
+        and model_to_save._tied_weights_keys is not None
+    ):
         for key in model_to_save._tied_weights_keys:
             if key in state_dict:
                 state_dict.pop(key)