I'm on ubuntu 12.04.
Recently I bought a cheap apple style bluetooth keyboard. It pairs OK. I paired it with the current 102 key still attached.
Anyway I noticed that the character mapping is incorrect. Most keys do not type anything - some keys on the right (k, l, ;') etc give numbers, but that's about it.
So I rebooted, with 102 kbd unattached, and the bluetooth keyboard on, ready to connect.
After boot at the login screen, the bluetooth keyboard had paired. I typed my password, and it logged in fine!! However after the user login was complete it reverted to the broken behaviour. A glance at the layout chart shows ubuntu thinks I still have the 102 layout, even though it remained disconnected.