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.
Phil Hardy, the British film scholar, calls the movie a "confused and over-ambitious offering from Grimaldi." He says that The Human Duplicators "marks the beginnings of a return to the technical gimmickry of the thirties. Thus, fittingly, it stars Kiel who became one of the more bizarre jokes in the later James Bond films, which were the ultimate in technological gadgetry."