diff --git a/moltemplate/force_fields/convert_OPLSAA_to_LT/oplsaa2lt_classes.py b/moltemplate/force_fields/convert_OPLSAA_to_LT/oplsaa2lt_classes.py
index c65fd6f..5dae4e9 100755
--- a/moltemplate/force_fields/convert_OPLSAA_to_LT/oplsaa2lt_classes.py
+++ b/moltemplate/force_fields/convert_OPLSAA_to_LT/oplsaa2lt_classes.py
@@ -198,7 +198,7 @@ def _duplicate_count_str(self) -> str:
         # acting on the same atom types, then
         # add a unique integer to the name of this interaction type.
         if self.duplicate_count > 0:
-            return f"_{self.duplicate_count}"
+            return f"__{self.duplicate_count}"
         return ""