In our school, our users move from computer to computer to view their emails in Outlook (MS Exchange 2003). This worked fine until we started using Win7 boxes along with our WinXP boxes. We have the same version of Outlook 2007 on all machines, and we do not use PST files.
Since our users have started using a mixture of Win7 and WinXP boxes, going back and forth, we've seen more than 30 people experience duplication of their default Outlook folders (Calendar, RSS Feeds, Contacts, Tasks etc). The latest - empty - folders are considered the new defaults, which means they cannot be deleted. My users have to move their old items to these new folders and then delete the old ones. Some of my users have up to SIX duplicates of default folders, it's a real mess. I need to stop this from happening.
I recreated this issue in the following way. I logged in as a test user on a WinXP box, opened Outlook 2007, logged out. Then I tried logging in on other machines. The first time I logged in onto a Win7 machine, I didn't get the issue oddly enough, but a few days later, when I tried again, logging in on Win7, opening Outlook 2007, then logging back onto the WinXP caused duplication of the default folders. Logging into yet another new Win7 box caused another set of default folders to appear, so now I have 3 of each. It seems to trigger on a machine where I open Outlook the first time and it populates folders. No error messages seem consistent with this occurence. My Account Settings and Data File Management setup look perfectly normal...