Also depends on how you want to use those credits. It will be 2 credit per person who is on the dining plan, but you could choose to pay for one person's meal using the dining plan and pay for the other person's out of pocket.
So lets say it's a reservation for two people. You tell the server you're on the dining plan but only one person will be using the dining plan and the other will be paid of out of pocket. So instead of it being 4 TS credits, it would only be 2 TS credits. You will want to make sure the most expensive things go on the person who will be using credits.