They are placed underneath the other users, and aren’t listed under any spesific roles. If I enter their user pages, “administrator” is what’s chosen in the drop-down menu, presumably bacause the drop down by its nature demands it to display something and “administrator” is first in the list, not because their role is really set to administrator.
Now that gave me an idea of what I think is causing this. As mailing out passwords doesn’t work from this test system, I’ve had to manually edit the user settings in WP (using my admin account of course) in order to give them a new password. What might be causing this is that when I access their user page in order to set a password, the user is given admin status because sneakily enough, “Administrator” is what is selected in the drop down when I update.