Duplicate mail problem, what to use?

[KliK]

OK, I have the problem with duplicate mails...the system crashed over the weekend, so i had to upload it again...all DATA were saved!

so now i have imported the messages in Opera, Incredimail & Outlook express - too many mails, so they are sorted in 3 different mail recevers...
and in some i have the duplicate mails...

how to get rid of them? is there some nice program you use for that?!

thanks for answers...