Its normal to see some people more than once in whose online and it was not intended to be a exact real-time statistics of where the users are.

If you don't log-out, the session table has no way of updating itself.

If you don't logout and just close the browser, you still going to be listed in users online on forum home page for the duration of the time-out set in admin CP

The same with who's online, if user closed the browser, then comes back to forum it will list him twice for some time untill his first session times out.

There must be the way to improve this hack to only show the latest session info for the user.

I think this hack needs at least one or two more improvement, Kevin knows what it is.