I've only noticed this on a couple of PCs. In the workstation object summary, the correct user shows up as the primary user, but the wrong user shows up as the logged in user. How do I know that user isn't logged in? Because my workstation is one of the ones with the problem.

Never mind. I just found that the workstation that the other user is using was not registered properly in dns, so that's probably what did it. I'm posting this anyway in case someone else sees this kind of problem.