diff --git a/litellm/utils.py b/litellm/utils.py
index 7947fbbe2..b87e399f1 100644
--- a/litellm/utils.py
+++ b/litellm/utils.py
@@ -1793,7 +1793,10 @@ def register_model(model_cost: Union[str, dict]):
 
     for key, value in loaded_model_cost.items():
         ## override / add new keys to the existing model cost dictionary
-        litellm.model_cost[key] = loaded_model_cost[key]
+        if key in litellm.model_cost:
+            for k,v in loaded_model_cost[key].items(): 
+                litellm.model_cost[key][k] = v
+        # litellm.model_cost[key] = loaded_model_cost[key]
         # add new model names to provider lists
         if value.get('litellm_provider') == 'openai':
             if key not in litellm.open_ai_chat_completion_models: