Dead Ringers (1988), Cronenberg

One of Cronenburg's best, Jeremy Irons's finest moment, and the greatest film about identical twin gynecologists ever made.

Iron's plays the Dead Ringers of the title - The Mantles, identical twin brothers who have remained inseparable into adulthood. They both work at their own gyno practice, only treating women - and confirming many of the troubling thoughts women watching this film will have at some point had about men who choose a profession which focuses entirely on women's sexual organs and reproductive systems. They often swap roles and pretend to be one another - the more confident and socially adept Elliot giving acceptance speeches and seducing women for his brother, the shyer but more technically brilliant Beverly. Iron's is just outstanding - he manages to create separate and believable characterizations of the Mantle twins, without their differences being too obvious. It's a triumph of Iron's acting that some of the creepiest moments of the film are the points when the characters become disconcertingly similar, the moments when the viewer is mistaken about which is which.

Genevieve Bujold plays love interest Claire Niveau was really good in this, and very familiar - but looking at her IMDB biog I can't remember seeing her in anything else.