I need to have two different userIds that map to the same local profile. What I really need is to have to users that are the same one.
Is this possible?
It would probably be better to only link the actual folders you needed since Windows is certainly not set up to do this.
The first problem will be permissions. You need to ensure that both users have the correct access permissions to the files and folders.
Even then, I'm not sure that the registry files are robust enough to be treated this way, it would be very easy to corrupt the profile so I would certainly not experiment on live profiles.
If you're simply looking for both to have the same user settings, copying the NTUSER.DAT file between accounts would work. Setup the first account as you wish, copy the NTUSER.DAT file into the other users account, login as other user and bingo, same setup. You could also setup a scheduled task to keep them in sync.