Outlook 2003 - When change contact and save creates duplicate

[Nick J]

Our office edits/changes outlook contact information often. When I edit a
contact and send it to someone else that already has the contact it does not
"overwrite" their existing contact, but rather just creates a duplicate.
(Ask to overwrite/check for duplicates is selected in options, BUT it doesn't
ask to overwrite and just creates a duplicate)

Any ideas would be greatly appreciated!!

Thanks