It is possible that a badge record at the main database may have been deleted by others since the mirror database snapshot was taken. If the changes to the mirror database includes a change to that same badge record, then the record will be recreated at the main database during the synchronization process.
It is equally possible that a badge record at the main database may have been changed by others since the mirror database snapshot was taken. If the changes to the mirror database includes a change to that same badge record, the subsequently revised record at the main database will be over-written during the synchronization process.
If you make changes to the field structure of the main database, by adding fields for example, and a mirror database exists from prior to those changes, then the mirror will not be useable and will be deleted with the revised main database is first opened.
Note that synchronizing the main database is not permitted if the main database was created by attaching to a database table not originally created by the badging program.