The Recent Visitors function doesn't perform any checking for dual accounts, though I suppose you could monitor it frequently and begin noting IP addresses of users...
The number of UNIQs per IP is a saftey check. Each user gets a unique session cookie set on their machine during the initial request. Some users block cookies. As a result, the unique cookie would be reset each time. These unique cookies are used to track the number of users, so you can imagine what would happen to the guest count if there was no maximum limit to the number of unique cookies handed out to a single IP address.
The cookies do expire after the session ends, though, so they can't be used as an effective method of determining duality.
There IS a hack on UBBDev that hijacks the login and logout forms and does some cookie magic to catch duals, but I don't think it's been updated since the 6.4 days... It MIGHT still work in 6.7.
![[Linked Image from navaho.infopop.cc]](http://navaho.infopop.cc/progress.gif)
