who(1) shows more than one user on the same terminal

[jidanni]

Is it normal to see two users on the same tty?
$ who
jidanni  pts/0 ...
ralph    pts/0 ...
jim      pts/1 ...
$ ls -l /dev/pts/0
crw--w---- 1 jidanni tty 136, 0 2007-08-17 00:58 /dev/pts/0

The administrator (Dreamhost) says
> You could potentially see many more than that at any given time.
> There are other users with whom you share the hosting, as well as
> the admins. This is normal.

Yes, many users, but not on the same pts/0?!
ps -u anybody_other_than_me won't show anything, so I can't
investigate further. Perhaps "stale utmp entries?"