Kiel himself seems to have had mixed feelings about the film. He said in an interview with American film scholar Tom Weaver that the film "was a big hit in Chicago," where it played "in like 27 theaters" simultaneously. Kiel made personal appearances at theaters that were showing the movie in Chicago and said that they were so successful that he was asked to do the same in Toronto. But he told interviewer Maggie Howard in 2009 that "The way the director wanted me to act - kind of robotic - didn't come off as well as I would have liked."
Spoofed on Mystery Science Theater 3000. Season 5, Episode 20.
The Human Duplicators' interior shots were filmed at Producers Studio in Hollywood. Exterior locations were Bronson Canyon in Griffith Park in Los Angeles and a school located at 5210 Clinton St. in LA, which was used as the Space Research Corp. building where the scientists work. The exact dates of filming could not be found, but the film was copyrighted by Hugo Grimaldi Productions on October 21, 1964.
The "tele-transporter" that transports Dr. Kolos to Earth is very similar to the transporters in 'Star Trek,' which debuted about 18 months after 'The Human Duplicators' was released. What's more, the story of duplicating people was used in the first season story, "What Are Little Girls Made Of?".