[Dx4win] How to erase dupes

[F6EXV]

Hello all !
I logged my operations from WH8 and WH6 with DX4Win.
I have replied to the direct request using the sequencing printing. So 
these contacts are marked as confirmed.
Now that the incoming direct requests have almost stopped, I would like 
to QSL all the log via bureau, with multiple-QSO labels.
So far, I can manage that... I guess I need to filter on QSO not 
confirmed, and change print flags.
But is there a way to eliminate duplicate QSOs before I set the print 
flags ? I mean eliminate from the printing, not from the log...
I do not recall any message about this... So thanks in advance for any 
help...
73
Paul F6EXV M0EXV AH6SF WH8/F6EXV WH6/F6EXV KH8SI and many more !