The narrative follows a very tall space alien (Richard Kiel) who has come to earth at the command of the "Intergalactic Council" to replace select humans with "android doppelgängers.

"[1] The goal of human duplication is to take over the earth, but the plan fails when the androids are destroyed by an investigator from the US National Intelligence Agency.

The police, meanwhile, are stymied by multiple thefts from high-security electronics facilities, apparently perpetrated by the "top scientists" who work at them.

After being admitted to his facility, he tears a security door off it hinges with his bare hands and kills a guard.

Glenn Martin (George Nader) of the National Intelligence Agency (NIA) takes over the case.

As she leaves, Glenn is attacked by an android version of Dornheimer's servant Thor (John Indrisano).

As he saws the bars, the real Dornheimer tells him that he can destroy the androids by zapping their heads with the lab's "pulse laser beam."

[6] The Human Duplicators was the color first feature on a double bill with the black-and-white Mutiny in Outer Space.

He wrote that there was little new in the plot, but that it "generates enough interest to pass in minor situations" and has "exploitation value" for theater owners.

"Whit" was somewhat complimentary about the production crew, noting that "Don Wolf's editing is fairly fast.

"[13] British film scholar Phil Hardy calls the movie a "confused and over-ambitious offering from Grimaldi."

[4] British critic Steven Puchalski refers to the film as a "colourful dose of swill" with a "silly plot and comical goofiness going for it."

He makes specific mention of the special effects, sarcastically noting that "The highly technical duplication process involves the victims standing in a circular cage while red and blue lights flash at them," after which "they sit under clear plastic hair dryers until their brains harden."

He adds that for unknown reasons the androids have heads made of plaster, "so whenever they're knocked on the noggin, their skulls crack open and Erector Set pieces tumble out.

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.