This is the question that astronauts Roy Thinnes and Ian Hendry ask themselves when they discover a parallel world of Earth always hidden on the far side of the sun in this 1969 cult science fiction melodrama, released here in America as JOURNEY TO THE FAR SIDE OF THE SUN. The plot of the film was devised by British writers Gerry and Sylvia Anderson, the creators of such TV shows as "UFO", "The Thunderbirds" and "Space 1999". It is exceedingly weird at times, betraying the influence of "The Twilight Zone" and even Stanley Kubrick's classic 2001: A SPACE ODYSSEY. The visual effects work of Derek Meddings, who would also later work on SUPERMAN: THE MOVIE, holds up surprisingly well under the last three decades of special effects advancements; and while they are not really on the same exalted level of the Kubrick film, they are very superb. If you don't anticipate a STAR WARS-type of a film and can overcome the occasionally trite dialogue, DOPPELGANGER is a good film; it was good enough for me to rank it a '7' and consider it an undiscovered sci-fi gem.