Some users experience duplicate items in their Exchange mailbox when mail has been migrated from a Notes Archive. Not all users will be affected and generally only a single folder may be affected in this way.
This could also happen for a Notes Mail file.
This could happen for any folder and not just one folder. The cause here was that the Sent items folder in Notes was still in V5 and had not been upgraded to V7 or later.
To resolve this issue upgrade the folder to v7 in Notes.
