The doubling of the registry key entries has happened to me (up to quadruple actually) and I think it might have to do with the preferences window not being destroyed on close bug, though more testign is needed... If you see these multiples, I suggest deleting the copies. (yeah, I know, deleting the copies of the shared file extentions can be very tedious.)

As to your problem of not seeing your shared files.... do you have "My shares visible" checked in the Tools menu? By default it's unchecked, and the only fiels you would see on the "Files" page are files you have downloaded.