Use once instead of on

IPython/html/static/components

@@ -1,1 +1,1 b''
-Subproject commit 563c9e74b153e9509d94fd448353eeda13f0819c
+Subproject commit 87ff70d96567bf055eb94161a41e7b3e6da31b23

IPython/html/static/widgets/js/manager.js

@@ -182,7 +182,7 b' define(['
         var id = utils.uuid();
         model.views[id] = model.state_change;
         model.state_change.then(function(view) { 
-            view.on('remove', function() {
+            view.once('remove', function() {
                 delete view.model.views[id];
             }, this);
         });