Hi Nathalie!
The conversion tool would be used for any SmarterMail release after 7. If you were on 7.5 or higher, a conversion is not required from what I understand. It should only be used when SmarterMail doesn’t move the items from the older version as expected. It's possible that things were duplicated because the conversion utility was not required? Did you try the migration without the conversion tool? What version did you migrate?
Andrea Free
SmarterTools Inc.
877-357-6278
www.smartertools.com