50s / early 60s Grade B Science Fiction

Hello. Looking for the title of a film about an astronaut that travels into space and is presumed lost. Miraculously, he returns but his behavior is off. Maybe replaced by an alien. He now has the ability to duplicate himself to literally be in two places at once. There seems to be a hidden agenda of trying to sabotage the exploration of space by humans. Thought the title was "The 4D Man", but I know for certain this film I'm asking about doesn't star Robert Lansing and Patty Duke. Thanks.