Yep, they can, thats why they have to implement something other than just buyer feedback. Like they started to charge for vendors accounts. I believe that they need to not charge for buyers accounts, but they have to spend at least 50 bitcoins from one account before they are allowed to open up another account. That way, they would be forced to keep the same account for at least a few purchases. I think thats the best answer..... or heck make it 100 bitcoins. there really shouldn't be a reason to be changing accounts so often... if for some reason you do, leave it up to SR to make that decision.