Index: /trunk/src/org/openstreetmap/josm/gui/tagging/presets/items/ComboMultiSelect.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/tagging/presets/items/ComboMultiSelect.java	(revision 16088)
+++ /trunk/src/org/openstreetmap/josm/gui/tagging/presets/items/ComboMultiSelect.java	(revision 16089)
@@ -363,5 +363,5 @@
     @Override
     public Collection<String> getValues() {
-        initListEntries();
+        initListEntries(false);
         return presetListEntries.stream().map(x -> x.value).collect(Collectors.toSet());
     }
@@ -372,5 +372,5 @@
      */
     public Collection<String> getDisplayValues() {
-        initListEntries();
+        initListEntries(false);
         return presetListEntries.stream().map(PresetListEntry::getDisplayValue).collect(Collectors.toList());
     }
@@ -378,5 +378,5 @@
     @Override
     public boolean addToPanel(JPanel p, Collection<OsmPrimitive> sel, boolean presetInitiallyMatches) {
-        initListEntries();
+        initListEntries(true);
 
         // find out if our key is already used in the selection.
@@ -396,7 +396,9 @@
     }
 
-    private void initListEntries() {
+    private void initListEntries(boolean cleanup) {
         if (initialized) {
-            presetListEntries.remove(new PresetListEntry(DIFFERENT)); // possibly added in #addToPanel
+            if (cleanup) { // do not cleanup for #getDisplayValues used in Combo#addToPanelAnchor
+                presetListEntries.remove(new PresetListEntry(DIFFERENT)); // possibly added in #addToPanel
+            }
             return;
         } else if (presetListEntries.isEmpty()) {