Go log into your BIS account and un-integrate the pop3/imap account or kill the forwarding rule.
Exactly. If you're forwarding and interogating then you'll get duplicates. You'll also get duplicates if collecting multiple addresses where one is part of a distribution group to the other (i.e. - Send an email to 'User 1' and 'IT', where 'User 1' is part of the 'IT' distribution group = 2 emails).