# UNDF: UNDF-2026-000000926
--- a/cw_monero/lib/monero_subaddress_list.dart
+++ b/cw_monero/lib/monero_subaddress_list.dart
@@ -16,7 +16,7 @@ abstract class MoneroSubaddressListBase with Store {
         _isUpdating = false,
         subaddresses = ObservableList<Subaddress>();

-  final List<String> _usedAddresses = [];
+  final Set<String> _usedAddresses = {};

   @observable
   ObservableList<Subaddress> subaddresses;
@@ -96,10 +96,8 @@ abstract class MoneroSubaddressListBase with Store {
   Future<void> updateWithAutoGenerate({
     required int accountIndex,
     required String defaultLabel,
     required List<String> usedAddresses,
   }) async {
-    _usedAddresses.addAll(usedAddresses);
-    final _all = _usedAddresses.toSet().toList();
-    _usedAddresses.clear();
-    _usedAddresses.addAll(_all);
+    _usedAddresses.addAll(usedAddresses); // Set auto-deduplicates
     if (_isUpdating) {
       return;
     }
--- a/cw_wownero/lib/wownero_subaddress_list.dart
+++ b/cw_wownero/lib/wownero_subaddress_list.dart
@@ -16,7 +16,7 @@ abstract class WowneroSubaddressListBase with Store {
         _isUpdating = false,
         subaddresses = ObservableList<Subaddress>();

-  final List<String> _usedAddresses = [];
+  final Set<String> _usedAddresses = {};

   @observable
   ObservableList<Subaddress> subaddresses;
@@ -104,10 +104,8 @@ abstract class WowneroSubaddressListBase with Store {
   Future<void> updateWithAutoGenerate({
     required int accountIndex,
     required String defaultLabel,
     required List<String> usedAddresses,
   }) async {
-    _usedAddresses.addAll(usedAddresses);
-    final _all = _usedAddresses.toSet().toList();
-    _usedAddresses.clear();
-    _usedAddresses.addAll(_all);
+    _usedAddresses.addAll(usedAddresses); // Set auto-deduplicates
     if (_isUpdating) {
       return;
     }