diff --git a/litellm/utils.py b/litellm/utils.py
index 7576e3bb83d..2e186bb160f 100644
--- a/litellm/utils.py
+++ b/litellm/utils.py
@@ -2779,7 +2779,7 @@ def register_model(model_cost: Union[str, dict]):  # noqa: PLR0915
                 litellm.anthropic_models.add(key)
         elif value.get("litellm_provider") == "openrouter":
             split_string = key.split("/", 1)
-            if key not in litellm.openrouter_models:
+            if split_string[-1] not in litellm.openrouter_models:
                 litellm.openrouter_models.add(split_string[-1])
         elif value.get("litellm_provider") == "vercel_ai_gateway":
             if key not in litellm.vercel_ai_gateway_models: