You can't sell what you don't own. Blizz will catch on -- I just hope they catch on BEFORE some ignorant buyer wastes his money just to get banned.

Furthermore, it's very possible the accounts were botted. Blizzard doesn't really care if you name your characters the same, and the "great starter gear" means they're in quest gear/greens. Naming your characters the same doesn't imply multiboxing, though it would be sad to know someone who multiboxed was breaking the rules in this fashion and potentially giving the rest of us a harder time reputation-wise.