If a user has copied a message from his sent folder or any other folder into another folder on Lotus Notes, then when migrating the message you will notice that the message is migrated twice.
This is due to the copy and paste action on Lotus Notes and not MNE.
When you copy and paste a message, it creates a new document with a new unique identifier (UNID).
As MNE see's these documents as different documents, both are migrated.
So MNE is operating as designed and is best to move the message and not copy it.
Further information is in this KBA:
https://support.quest.com/migrator-for-notes-to-exchange/kb/74263
Additionally a migrated user could also have duplicate emails appearing in their Outlook, if that user account was added to 2 migration batches that were performed at the same time on different servers.
Just remove the user account from another migration batch.
Note: By default, MNE should not migrate items that were already migrated. Migrator for Notes to Exchange contains Smart Re-migration technology, so that previously migrated items are detected and not duplicated if they are inadvertently migrated again.
- For calendar items (appointments and tasks), MFNE uses the “ApptUNID” field, shared by all the event’s documents, as the ID.
- For non-calendar items, MFNE uses the UNID of the document, formatted as “OFxxxxxxxx:xxxxxxxx-ONyyyyyyyy:yyyyyyyy”, as the ID.
Further information and checking if the default re-migration setting is in place can be found in this KBA:
https://support.quest.com/migrator-for-notes-to-exchange/kb/14920
