I remember some time ago I had two versions of TG2 installed, but one was an old technology preview version, and the other was the currently released TG2 Deep. I had no problems uninstalling the older one, but they were in different directories. Actually if your worried, just copy your key file to a safe place, uninstall both versions, and start from a clean install of the latest TG2 release (that's what I would do). Actually when you do an uninstall it should leave your key file alone anyways.