Importing from Address Book to Contacts causes Duplicates

[Nerd]

I'm running Outlook 2000. I imported all the data in my Personal Address
Book to my Contacts. All of data imported fine, however it created 3
or 4 duplicates for each of my Contacts. I figured that maybe it was
due to the personal distribution lists that I had in the personal
address book. I went ahead and deleted the duplicates in my Contacts,
and a week later they reappeared.

2 Questions:

1) How do I stop the duplication?
2) How can I easily remove duplicate Contacts rather than deleting them
one at a time (I have hundreds!)

Thanks for the help!