Journey to the Far Side of the Sun

Anyone old enough to remember this one? I think circa 1971 featured Roy Thinnes bumping into his doppelganger in the parellel universe in our orbit but opposite position of solar path. His mission commander kept demanding to know why he'd turned back (it seemed to have only taken half the time for the trip) and I remember being spellbound when the 'other' earthlings started reading backwards! The turkey of all time had to be "The Thing with 2 Heads" featuring the unlikely duo of Ray Milland and Rosy Grier. I recall thinking that both must have been needed money fast to have done that dog.....