diff --git a/scripts/developer/debugging/debugWindow.js b/scripts/developer/debugging/debugWindow.js
index 4390cf1f77..068efb351b 100644
--- a/scripts/developer/debugging/debugWindow.js
+++ b/scripts/developer/debugging/debugWindow.js
@@ -15,6 +15,7 @@ var scriptData = ScriptDiscoveryService.getRunning();
 var scripts = scriptData.filter(function (datum) { return datum.name === 'debugWindow.js'; });
 if (scripts.length >= 2) {
     //2nd instance of the script is too much
+    ScriptDiscoveryService.stopScript(scripts[1].url);
     return;
 }