.
That does not help you. Rejection is still common with allograft. The difference is that it does not tend to be fatal. One still needs to match tissues. You may be confused because at time bone is the organ that is transplanted via allograft. In that case the bone is essentially dead, in fact transplants from cadavers are common. I am betting that any living material has to be killed for that to happen.
Try again.
Skin is a living organ. It is the largest organ in the human body. There was no rejection which was unusual, it was as if the cheetahs were identical twins.
Instead of digging your hole deeper you should be asking questions politely and properly. Using a transplant that you do not understand only makes you look worse:
Autograft vs. Allograft
"An allograft is a bone or tissue that is transplanted from one person to another. They typically come from a donor, or cadaver bone."
Just for fun I did a bit more research on bones used in allografts:
"While allograft bone only provides a calcium scaffolding, does not have any bone-growing cells or bone-growing proteins required to stimulate new bone growth, and thus has a lower chance of fusion as compared to using the patient's bone, it has proven comparable in certain studies to autograft in terms of producing successful fusions."
Allograft: Cadaver Bone from a Tissue Bank
Are you picking up your ideas from lying creationist sites? Those are usually very easy to refute. I suggest trying to honestly learn for once.