Index: trunk/src/org/openstreetmap/josm/data/validation/tests/DuplicateRelation.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/validation/tests/DuplicateRelation.java	(revision 15374)
+++ trunk/src/org/openstreetmap/josm/data/validation/tests/DuplicateRelation.java	(revision 15375)
@@ -110,6 +110,6 @@
      */
     private static class RelationMembers {
-        /** List of member objects of the relation */
-        private final List<RelMember> members;
+        /** Set of member objects of the relation */
+        private final Set<RelMember> members;
 
         /** Store relation information
@@ -117,5 +117,5 @@
          */
         RelationMembers(List<RelationMember> members) {
-            this.members = new ArrayList<>(members.size());
+            this.members = new HashSet<>(members.size());
             for (RelationMember member : members) {
                 this.members.add(new RelMember(member));