Why doesn't 'who -q' work properly???

[Guangliang He]

The following is the output of the 'who' command with and without -q
option.

% who
user1	console      May 18 08:30
user2	tty01        May 17 22:31
user3	tty03        May 19 08:35
user4	tty06        May 19 07:28
% who -q
user1 user2 user3 user4 user4 
# users=4

Can anyone explain why the 'who -q' gave a fake user 'user4' but saying # of
user = 4 ?

Thanks a dozen
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