Mail journalling creating duplicates

I have enabled mail journalling with output going to a mail-in db.We have several ‘dummy’ groups whose sole member is a central mail-in database. All mail getting sent to these ‘dummy’ groups is getting duplicated in the journalling db. Also, all mail sent to people in an alternate internet domain is getting duplicated. In all cases the mail is being routed on the same server.

Does anybody know any server .ini parameter or other way to stop this duplication?

tia

Tony