fixed #490

blocks.js

@@ -6504,7 +6504,7 @@ InputSlotMorph.prototype.collidablesMenu = function () {
         allNames = [];
 
     stage.children.forEach(function (morph) {
-        if (morph instanceof SpriteMorph) {
+        if (morph instanceof SpriteMorph && !morph.isClone) {
             if (morph.name !== rcvr.name) {
                 allNames = allNames.concat(morph.name);
             }

history.txt

@@ -2186,3 +2186,4 @@ ______
 * GUI, Objects: add keyboard shortcut for “new project”: ctr-n
 * revert changes made for JSLint’s sake after the issue was fixed in JSLint
 * Blocks: change “delete” behavior in context menus to only delete this particular blocks (and reconnect the next block to the previous one)
+* fixed #490