Need help identifying an old sci fi or fantasy novel

[pokerfan]

2. Reminds me of a movie if that helps

Doppelgänger (1969)

Eventually, Ross assembles a series of clues that point him to the conclusion that he is not on Earth, but indeed on the unknown planet — a Counter-Earth that is a mirror image of his. Many, including his wife, Sharon (Lynn Loring), are baffled by his claims that all aspects of life on the planet — from the print in books to the plan of his apartment — are reversed. However, Webb is convinced of the truth when Ross demonstrates the ability to read aloud from a sign, without hesitation, when it is reflected in a mirror. Later, X-rays from Kane's post-mortem examination reveal that his internal organs are located on the wrong side of his body. Ross conjectures that the two Earths lie parallel, which would mean that the Ross from the Counter-Earth is living through similar experiences on the far side of the Sun.

http://en.wikipedia.org/wiki/Doppelg%C3%A4nger_%281969_film%29