The Astral Twins by Laurence Burton

Twenty-six thousand years ago, the Atlantians evacuated Earth, escaping cataclysmic events that changed the planet. They have now returned to study the next evolution of human beings. They are shocked when they see the state of a world in bitter conflict, are appalled at the pollution and the abuse of natural resources, and cannot understand poverty in a world of abundance. GanaLozMiha is the scout for the Atlantians space nomads and is sent to discover how this state of affairs came about. He is tricked into landing and becomes incarnated inside a human being in a coma, Scott Bradley FitzLiam. The Earthman joined the military at an early age and was privy to the most sensitive information. In FitzLiam's body, the Spaceman settles on Earth, marries, and has two children. When the marriage breaks up, he nearly dies, which finally triggers the Earthman out of his coma. With two minds in one head, The Astral Twins at first battle for domination, until they come to terms with their predicament and become allies. Each man has his own agenda. The Spaceman is interested in how humans got themselves into their current state, while the Earthman wants to learn about the space nomads and understand how their flying saucers work. When the Spaceman and Earthman finally separate, they continue on in a way that neither could have imagined.