Created Issue: Superimposing views when double-tapping back on Windows Phone 7 [11074]

I do the following navigation pattern:

Navigate into the app (and it's main view)
Go into a detail view that fetches something from a REST server (that is - it shows a progress indicator for a few seconds)
While progress indicator still is shown, I click the back-button twice in quick succession (easy to do by mistake)
The app returns to the main view, but with the content of the detail view superimposed on it.

This was recreated both on a Nokia Lumia 800 and HTC Titan.

There is no exceptions (or anything else) shown in the output. The only thing happening in the OnNavigatedFrom() method of the detail view is nulling out the background image (for memory reasons). It happens in other views as well.

My idea is that the draw method on both views are called on different threads, leaving only the main view to be responsive.

I am using the Silverlight Toolkit for WP7's TransitionFrame in my app. When I remove this, the error removes itself - but the transitions are more important to me than this error.

Can you please fix this in the next update?