Index: trunk/src/org/openstreetmap/josm/gui/dialogs/properties/TagEditHelper.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/dialogs/properties/TagEditHelper.java	(revision 7157)
+++ trunk/src/org/openstreetmap/josm/gui/dialogs/properties/TagEditHelper.java	(revision 7158)
@@ -163,4 +163,5 @@
      * If during last editProperty call user changed the key name, this key will be returned
      * Elsewhere, returns null.
+     * @return The modified key, or {@code null}
      */
     public String getChangedKey() {
@@ -760,5 +761,5 @@
             for (OsmPrimitive osm: sel) {
                 String val = osm.get(key);
-                if (val != null) {
+                if (val != null && !val.equals(value)) {
                     if (!warnOverwriteKey(tr("You changed the value of ''{0}'' from ''{1}'' to ''{2}''.", key, val, value),
                             "overwriteAddKey"))