Duplicate entries in outlook 2007

I have a user that is running on a Macbook with  Entourage 2008 as well as a parallels session running Outlook 2007. This is connecting to an exchange 2003 server. at some point in the last few weeks his outlook started showing duplicates of his inbox sub folders, contacts and calendar entries. I reinstalled outlook and rebuilt the profile and the duplicate sub folders were cleared (with exception of the sync issue folder), but the duplicate calendar entries and contacts still remain. He is also mentioning that some emails are showing up in  Entourage, but not on his outlook. Any ideas as to what caused this and what to do about it?

An additional note about the dupe contacts, not only are the named contacts duplicated, but now there are entries added that have no name associated with them, just email addresses. His contacts have essentially tripled.