There is a possibility that you might get more than the 12 TPU from depositing both sides of the lockoff separately. But that depends on the features of each side; and the supply-demand and amount of time before the check-in date, it gets deposited. E.g, if one side is a studio, you won't typically get as much for, as if it was a full kitchen or mini-kitchen.
If you can give us the Resort Number, week and unit number; someone can look them up on RCI's TPU calculator.
You will need to call an RCI VC the first time you deposit a lockoff, since the info ultimately gets permanently entered into the new TPU deposit page, the first time you do it. RCI will subsequently confirm with the resort, that you can actually make the deposit and will request it be released from the resort. (Sometimes the resort will require that maintenance fees be paid in advance,before they will release the units to RCI, but that is actually dependent on the resort policy.) Most of the time that's all you need to do since the resort knows what you deposited, but the first time you might check with the resort to make sure since a few are a little different.