Anyone ever see this before?

Bes 4.1.6
Exchange 2003

Moved a bunch of users over the weekend; now all of their calendar entries are doubled on their devices but not in Exchange.

On phone with t-suport now. So far they wanted to blame Cached exchange mode and they wanted me to reset the devices by hand... Still waiting for a better answer.

One device we did a calendar reset/resync and that fixed that device, but still a manual process that we shouldn't have to go through. Have many more devices to migrate...