Duplicate Email in Outlook 2003 even with the patch

I called Microsoft for the patch to fix this problem, even installed it under
their tutelage just to make sure I was doing it right, but it has not helped.
I keep getting duplicate messages. Not leaving messages on the server(s) is
not an option because:
a) some accounts are checked by other people besides me
b) I need messages available on webmail

Anybody know how to fix this?