I would have argued that the resurrected person was the same person as the original because God declared it so. But that doesn't work.
JWs actually believe that God will make an identical copy of the person as he or she was at the time of death, complete with memories and all other personality traits unique to that individual. Problem is, the copy is still a copy -- a clone, really -- and a copy, no matter how perfect, is not the original. Even if you could make an identical copy of say, a written letter, and you destroyed the original, the copy would still be a copy. And if you could electronically record every detail of the original, then destroy the original and later reproduce an identical copy from the stored information, you'd still just have a copy. Even if God himself declared that the copy was the original, it wouldn't be so.
Same goes with people. JWs will argue, "No, God can do anything", but that doesn't cut it. This is easy to show. Suppose God, right now, made a perfectly identical copy of you and stood him right next to you. Being a perfect copy, the copy would think he was the original. But he wouldn't be the original. You are the original. Even if God declared that the copy is the orginal, it wouldn't be so. Now extend the analogy a bit. Suppose God made 10 perfect copies. All of them would think they were the original, and all of them would be wrong. Now extend the analogy again. Suppose God perfectly recorded in his memory every detail of you. You die and and no longer exist for say, a million years. God then creates 10 identical copies of you, all of whom think they're the original. But none of them are. Now suppose that God creates just one perfect copy a million years hence. That would still not be the original you, just as none of the 10 would have been you. Therefore, if you go completely out of existence, you cannot be resurrected. A copy can be made, that that's not a resurrection. For a true resurrection to occur, there must be physical continuity of some aspect of a person's existence.
This thoroughly disproves the JW notion of either the resurrection, or of their claim that when you die you go completely out of existence, or both.
AlanF