This has been frustrating me for a few days now. If you have an extra address book / contact list on your Blackberry that you can’t seem to delete in any way, you can force it to resync from the server.
This is caused when someone moves or re-adds a BB user to the BES without wiping their Blackberry before reactivating. This will create a new contact list each time. To remove it, go to Contacts and click Options. Then type rset, it will pop up with a screen asking if you want to wipe the contacts, select yes through all windows. You can then wirelessly sync or use desktop manager to repopulate contacts.