fix: aggregate Global Leaderboard by model to prevent duplicates

app.py

@@ -69,13 +69,13 @@ class LeaderboardManager:
         # Calculate averages for numeric columns
         model_aggregated = self.leaderboard.groupby('model_name')[numeric_columns].mean().reset_index()
         
-        # Sort by composite score and add ranking
-        top_results = (model_aggregated
-                      .sort_values('composite_score', ascending=False)
-                      .head(n)
-                      .reset_index(drop=True))
+        # Sort by composite score (descending) to get proper ranking
+        model_aggregated = model_aggregated.sort_values('composite_score', ascending=False).reset_index(drop=True)
         
-        # Add ranking column
+        # Take top N results
+        top_results = model_aggregated.head(n).copy()
+        
+        # Add ranking column (1-based ranking)
         top_results.insert(0, 'rank', range(1, len(top_results) + 1))
         
         # Reorder columns according to configuration