Where do BCC Dropbox messages go when there are duplicates?

Where do BCC Dropbox messages go when there are duplicates?

HI
I like the new BCC Dropbox feature as i have never been able to get the Outlook plug in to work.
However, when i send an email to BCC Dropbox and the person that I'm sending it to has duplicate entries in the CRM I find that the email does not get stored against any of them.
Is there a way to work around this or have i just got to get rid of all the duplicates?
many thanks
Kate