Sorry my friend, I am perplexed over your situation. You have paid for one connection that means you can only run one streaming box at a time. Saying your supplier only allows 2 boxes on a sub does not appear to be accurate information. What I am saying is, the supplier controls connections, that means if you loaded the same SUB on 10 boxes, who cares, you could only watch one box at a time. If you turned on two boxes with one connection, the stream would begin to glitch, that is how the supplier would get you to pay for another connection. There is no limit as to how many boxes you can load the same sub, it is all controlled through your connection limitations.
His supplier uses the unique MAC address of two devices to limit the amount of devices the login can be used for.
so in his case, yes there is a limit.