[TigerLikesRooster]

Your comment reminds me of the tale of two-headed birds. It is the legend told along Silk road. There were a bird with two heads. They share the same body. If one tries to kill the other, both would die. However, two heads hate each other so much that they fought all the time. In the end, one killed the other, killing them both:

The painting of two-headed birds

[april15Bendovr]

That's no way to get a A-"head" in life

[weegee]

The Soviets did the same experiment grafting the head (and front limbs) of a dog onto another dog. The dogs didn’t get along at first but they had to learn to “deal” with the situation. The dogs did live for awhile but I think the longest such grafted pair lived 3 weeks.