Only merge new entities/edges during gleaning

- Restrict gleaning to new entity names
- Only add edges with new keys
- Prevent similar decription of the same entity or edge

lightrag/operate.py

@@ -613,10 +613,12 @@ async def extract_entities(
                 glean_result, chunk_key, file_path
             )
 
-            # Merge results
+            # Merge results - only add entities and edges with new names
             for entity_name, entities in glean_nodes.items():
+                if entity_name not in maybe_nodes:  # Only accetp entities with new name in gleaning stage
                     maybe_nodes[entity_name].extend(entities)
             for edge_key, edges in glean_edges.items():
+                if edge_key not in maybe_edges:  # Only accetp edges with new name in gleaning stage
                     maybe_edges[edge_key].extend(edges)
 
             if now_glean_index == entity_extract_max_gleaning - 1: