I was to quick removing v5 after installing v6. I am missing some plugins. So, I have been putting back a backup with all v5 acymailing tables. But somehow it lost track of which Joomla users were already imported. So, I have about 750 acymailing users, and 800 Joomla users. Previously during import it would only import new added Joomla users, but after putting back the backup it imports all 800 Joomla users, resulting in a lot of double entries. Any ideas how to fix this?