two machines, same key

["John Doherty" <jld@jld3.net>]

Hi, yesterday I made a mistake and I'm not sure how to fix it without 
resorting to --nuke (which would not actually be catastrophic).

I have one machine, let's call it A, that has been running tarsnap from 
cron for a pretty long time. Yesterday, I made a replica of this 
machine, B, without stopping to think about the implications for 
tarsnap. Since B is mostly a replica of A, they both have the same keys 
(it's not strictly a replica: they have different IP addresses and 
hostnames).

They both tried to run tarsnap at the same time. B succeeded and A 
failed with "tarsnap: Sequence number mismatch creating checkpoint: Run 
--fsck", which is understandable.

The current state of affairs is that B can run tarsnap --fsck but A 
cannot. If I try, A reports:

tarsnap: Sequence number mismatch creating checkpoint: Run --fsck
tarsnap: Error fscking archives
tarsnap: Error exit delayed from previous errors.

The desired state of affairs is that A can run tarsnap again and B does 
not need to. I've disabled the cron job on B, so it won't run again 
unexpectedly.

Not sure what to do. Maybe rename the tarsnap-cache directory on A and 
let it create a new one?

Thanks for any advice.