Hello @user27939 ,   It would depend on the report. Individual drilldowns like All Opens for an email may contain "dupes" if a contact is opening the email multiple times, for example. If you're just exporting an email list, then there wouldn't be dupes since a contact can't appear on a contact list multiple times.   If you're sending a single email campaign to multiple lists, our system checks for any contacts (unique email addresses) in multiples of those lists. That way a contact is only receiving the email once, unless otherwise explicitly prompted for an automated or manual resend. ... View more