It depends. We have two contracts from Disney and two resales. They are all the same use year, so all the contracts have the same number with a 0, 1, 2, or 3 appended on to the end of it. We have the same member ID for all of them and they all show up on the computer when we call in. In fact, our two BWV contracts (one from Disney, one resale) come up as one lump sum of points, but if we ever wanted to sell one, it's still deeded as its own contract.
If the new contract is in a different use year, I believe you will have a second contract number for it.