Revert "rm hardcoded same score check"

This reverts commit f02c24204d.

environments/answer_format_environment/answer_format_environment.py

@@ -3653,6 +3653,14 @@ class AnswerFormatEnv(BaseEnv):
                     )
                 await self._save_failed_rollouts_to_jsonl()
 
+        # Check if all scores are the same (no learning signal)
+        if all(group_scores[0] == score for score in group_scores):
+            if self.debug_logging:
+                self.logger.debug(
+                    "All scores are identical, returning None for learning signal"
+                )
+            return None
+
         # Track successful groups for equivalent ratio enforcement
         if self.ensure_equivalent_ratios:
             # Count this as a successful group if we have any successful examples