You can have non-exclusive rights settings from the GPO.
You’ve no doubt totally reset the folder permissions by re-applying it this way, if you need access to the redirected folders as an admin or backup op for example, make sure the user is the “owner” of their folders in the advanced security options of the root of the redirection folder for each user.
I’ve just setup an SBS2011 server which sets up folder redirection for you but didn’t grant anyone else access to their redirected folders by default. I had a few niggles trying to setup access for admin to get at these folders, which involved taking ownership of individual’s directories, adding extra required permsissions and infact broke the functionality at first. The fix was indeed to change the ownership of the directories back to the user, and make sure ownership and new permissions inherits through their directory!