Note the auto mode (which is default) will show the item only when the viewport is shrinking to a size where the toolbar item is not visible.
Also, note that both overflow and normal templates are rendered to the DOM and same DOM elements with same IDs is not suggested to be used.
Check out this dojo here: http://dojo.telerik.com/aBAPi/20.
On a side note, due to UX best practices, when it comes to dropdown-like tools in the overflow, we recommend rather using plain buttons that open a dialog of some sort with the more complex tools instead of using them directly in the overflow part. Or, if the overflow functionality is to be used in mobile only, you can safely use the native select element.
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