Any tricks for cleaning up duplicate calendar entries? (Zimbra OSE)

[awnz]

I run a Zimbra OSE install for a primary school in NZ.

Our principal has a Nokia N8 smartphone, we use Funambol to synchronise. He is the only user using this particular arrangement.

We had a problem with this last night - our backup routine is supposed to stop Zimbra before doing an incremental bacup on /opt/zimbra using Areca Backup, then starting it again when done, but for some as-yet-undiscovered reason this got stuck with Zimbra down for several hours.

When the backup process was killed, Zimbra was manually started and this user went to sync from his phone, everything in his pretty full calendar got duplicated.

This is going to take ages to clean up manually, so I was hoping someone in the community had knew of any tricks to clean up duplicate calendar entries?

For the record, the address book was not duplicated, just the calendar.

Unfortunately because the backup failed, I can't use that to restore from, and due to SSH certificate issues caused by the server handling backups being rebuilt recently, the next available backup is over a week old, which is a bit too old to restore from. And yes, my next stop will be the Wiki for better backup methods so this doesn't recur, but in the meantime I have to clean up this user's calendar.

Any help/tips/ideas/pointers much appreciated!

edit: removed some language ambiguity (it -> ZImbra)