Doppelgänger (1969)

Director: Robert Parrish
Cast: Ed Bishop, Franco De Rosa, George Sewell, Ian Hendry, Loni von Friedl, Lynn Loring, Patrick Wymark, Roy Thinnes

Synopsis:

A planet is discovered in the same orbit as Earth’s but is located on the exact opposite side of the sun, making it not visible from Earth. The European Space Exploration Council decide to send American astronaut Glenn Ross and British scientist John Kane via spaceship to explore the other planet.