Working title: "Gemini". The studio didn't like it, and so switched to "Twins". This was changed to "Dead Ringers" after Ivan Reitman, who had produced two of Cronenberg's early films, approached Cronenberg about purchasing the rights to use the title "Twins". Twins was then used for the Danny DeVito/Arnold Schwarzenegger film Twins.
During filming, Jeremy Irons kept track of whether he was playing Elliott or Beverley by always playing one with his weight on the balls of his feet and the other with his weight on his heels.
William Hurt was Cronenberg's first choice to play the twins. He regretted turning it down but had a scheduling conflict. He later commented about turning down the roles by saying that he "had a hard enough time playing one character, let alone two".
The trivia items below may give away important plot points.
The movie is based on two real life twins, Stewart and Cyril Marcus. The two were found dead in their apartment on the Upper East Side of Manhattan. Their deaths were due to withdrawal from barbiturate addiction. The story is told in the novel "Twins" by Bari Wood and Jack Geasland (published 1977).