This add-on is worthless and TBH I feel stupid for having purchased it. It doesn't catch almost anyone, except constantly registering me as a dupe account whenever I use the "login as user" add-on (which I can't really fault the author for). But the original multiple account detector catches 5 for every 1 this add-on does (checked for false positives), and I've given it ample time to have planted cookies, etc., on the current users that are being caught. Honestly a waste of money, will not be renewing my license. Disappointed. :(
If you read our FAQ here, you can see that this add-on is not compatible with all third party "login as user" add-ons and will correctly report a multiple account if you login as another user (as this is the purpose of this add-on).