Does it matter?
Well with most of them I would guess Nils tracks them through their IP addresses that are supplied to the site automatically. There are ways to get around this but not many people know how and I will not enlighten them as to those ways.
And why respond to this topic that was only posted a month ago anyhow? Does it matter to me NOW? No.
While it was a lapse in vigilance to not notice that this was posted a month ago, it should surely be important still since you didn't get an acceptable answer until yesterday.