My offline machine runs armory 0.88.1 on ubuntu 10.04 which now won't sign transactions from my online 0.92.3 on ubuntu 12.04.

For ice-cold reasons, I'd rather downgrade my online than upgrade my offline (is that a song?) but it's tricky. I've downloaded the .deb file for 0.91.2 but it leads to the software centre where it stops because it notices that I already have a more recent version. What can I delete/rename to let it install and revert to .91? I don't want to just clean it all off and lose the blockchain and databases. Thanks.