Tom AU was an almost an exact copy of Tom, he's known to have come from an Alternate Universe. He still sells the same things. You can enter the back-room to find a room full of stand disks and boxes.
You used to be able to find Tom AU in the Alternate Universe, that could be visited by going on a portal over the fountain.
He looks exactly like Tom but with a purple colored shirt and the iconic tin-pot. He also had a £ symbol on his torso just like the original version.