They absolutely log your MAC addy. I am sure that is how they come to the coin lock conclusion. I have 3 PC's in my home, If I sign in to the same account consecutively from two different ones it gets coin locked. Same IP. On the other side of it, if I purposely change my IP to a different one, nothing happens. I am assuming (have not really researched this to say 100%) because they store the PC's mac address. THis way they know if you are logging in from a different PC. Which, for shits and giggles I am going to start logging into my 3 new accounts running a random MAC spoofer..... ;-)