I have tested 2 different emails, both are duplicated, but have different header.
The first one,
amavis: (26497-03) Passed BAD-HEADER, <web@server> -> <my email>, quarantine: U/badh-Uo+mu32fsdf, Message-ID: <msg id>, mail_id: etc..
The other one, looks better but still duplicated
amavis: (27881-08-2) Passed CLEAN, <firstname.lastname@example.org> ->, Message-ID: <msg id> etc...
I still don't see the cause, and don't know the solution.
Btw, how can I copy the line?