Duplicate Calendar and Tasks folders in Outlook 2003

Hi,

One of our users have this strange problem. We upgrated his email client to
Outlook 2003 (old one was Outlook 2000) and exchange mailbox was moved from
Exchange 5.5 to Exchange 2003 and now he has two Calendar and Tasks folders.
The "new" ones are his primary folders and are offcourse filled with nothing
=(

So when someone is trying to process an meeting request for him, all he has
in his calendar is free time, while his "older" calendar is filled with
meetings. What should I do - he has two separate machines - desktop with no
cached mode in it and notebook with cached mode installation.

Please do help me - as soon as possible; offcourse =)

Jouni