This looks like a timezone handling problem with repetitive all-day events.

I think this issue has actually been fixed a couple of days ago. However, this implies that only the new events will be fixed. What you can do to overcome this problem is to backup and restore the user events with the sogo-tool utility. Please try that and get back to us...

The sogo-tool bug is unfortunately another issue that we need to fix. Is it possible for you to edit those events via Lightning and see if the problem still occurs in the web interface? Use a recent version of SOGo for that test.

I'm sorry, it was case of my colleague...
He told me that he created event with repeating in SOGo WebGUI, then he synchronized calendar via Funambol with PDA, he made change in one occurence only and after some other synchronizations he had two same events and it was impossible to delete one of them. After some other synchronizations problem was gone.
Now he cannot reproduce it, because sync doesn't work for this case:
Now when he creates repeating event (every Sun, 10-11, for 2 months), sync with Funambol => sync is OK.
Then he changed day (Sun -> Thu) in one occurence only. Then sync with Funambol => and he sees no change on PDA side.
This is some other bug, I will verify it and if it will works same for me, I will create new issue...

So - I think you can close this one.

Thanks,
Milos

Request to close the issue from the reporter.