diff --git a/chemlactica/mol_opt/utils.py b/chemlactica/mol_opt/utils.py
index 23d7fcc..04d0953 100644
--- a/chemlactica/mol_opt/utils.py
+++ b/chemlactica/mol_opt/utils.py
@@ -107,7 +107,7 @@ def add(self, entries: List, diversity_score=1.r9):
             insert = True
             for e in new_optim_entries:
                 if (
-                    entry == e
+                    entry.last_entry == e.last_entry
                     or tanimoto_dist_func(
                         entry.last_entry.fingerprint, e.last_entry.fingerprint
                     )