[sync] Horde4 calendar sync duplicates

[Simo]

Hi,
I recently upgraded from Horde3 to Horde4 and that created sync problem for me.
I'm syncing calendar between Nokia N9 and Horde.  I have tried both syncevolution and buteo in N9, same behaviour.  The sync mode is two-way.

If I create event in N9 and sync, event gets created to Horde4.  However, on second sync, that event gets duplicated in N9. No duplicates in Horde4.  Also, when creating event in Horde4, no duplicates get created by syncing.

Looking at syncevolution output from second sync there is almost duplicate of the original item, but the UID field of VCALENDAR is different.

When either of the duplicate events is removed in N9 and synced again, event gets removed from Horde4 and don't appear there with next syncs.

Is it normal that event UID is different in Horde?

I'm running "Horde Groupware Webmail Edition 4.0.6", Kronolith version is 3.0.15.  Apache web server is latest one from Debian squeeze.  Syncevolution is version 1.2.2.

With Horde3 syncing with syncevolution worked without duplicates.  Any pointers where to look for solution are welcome.

Thank you,
Simo