Questions About Programming Key Fobs

2006 Prius

I have a working key fob.... works with the SKS stuff and it locks/unlocks the doors fine... works as it should. I bought 2 used OEM silver logo FOBs. Doing part 1 of the Chicken Dance routine, I was able to get both of them to start the car with the FOB in the slot. However when I do part 2, I get all the way to the end when you press & hold the lock button and the locks are supposed to lock/unlock once indicating that it's been successfully done.... and they lock/unlock twice which seems to indicate that the programming has failed. I've done it a dozen times... same thing. I bought a new shell, did the transplant surgery (both the chip and board), cleaned off the board with a Q-tip... and I get the same thing.... lock/unlock twice.... fail.

I've read that a possible problem is that there can only be 4 FOBs programmed to a car. And that if there are 4, someone with one of those programming gizmos needs to do their thing to clear out all 4 keys, add the original and then I'll be able to add another key.

My questions are.... is there a way that I can find out how many keys are programmed to my car? And is there another way that I can clear any other keys from the car? Is there some other way I can program these FOBs? Does anyone have any suggestions? If Rob happens to see this, I have a feeling you'll say that someone with a programming gizmo will need to clear out the memory and start over.