Index: trunk/src/org/openstreetmap/josm/gui/dialogs/properties/PropertiesDialog.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/dialogs/properties/PropertiesDialog.java	(revision 2950)
+++ trunk/src/org/openstreetmap/josm/gui/dialogs/properties/PropertiesDialog.java	(revision 2951)
@@ -267,4 +267,7 @@
             value = null; // delete the key instead
         }
+        if (key.equals(newkey) && tr("<different>").equals(value)) {
+            return;
+        }
         if (key.equals(newkey) || value == null) {
             Main.main.undoRedo.add(new ChangePropertyCommand(sel, newkey, value));