While I can't speak to what could have caused this, there should be an easy fix:
- Navigate to Apps
- Find Import/Export/Clone in the apps list
- Select the "app status" (gear) icon next to the app
- Use the Remove button on the app status page to remove the Import/Export/Clone app, then try cloning your rule again.
Going back to possible causes: opening an import/export/clone in multiple tabs/windows at the same time could cause problems, though I'm not sure if this specific problem is one. It's possible there is some other bug that got you here. Bruce may be able to figure out more from the internal app data if you care to keep that (or he wants to look--the above is an easy workaround).
In any case, this is almost certainly not the result of database corruption, so a restore is unlikely to help (unless it's to a database from before the Import/Export/Clone utility was put into this state, though it's certainly not the simplest approach to solving this problem...).
