Replication problem: How to sync?

Hi!

I have two replicas of my DIT, which unfortunately got out of sync
somehow. So I can spot a particular object where one attribute has a
different value on one replica than it has on the other one.

What would I do to find out how that could have happened?

What would I do to fix this? (Other than manually deciding which data is
the right one and overwrite the other; I guess this may not even fix it
for the next update.)

Regards,
Torsten