The Scapegoat (1958 Robert Hamer & scr)

Based on a Daphne du Maurier novel, adapted by Gore Vidal, in which jaded teacher Alec Guinness on holiday in France bumps into his exact lookalike, who drugs him and forces him to adopt the other character's life, complete with work problems, a fraught marriage and mistress, all of which the new character faces with some equanimity.

The effects are good, Guinness as reliable as ever in dual role. With Bette Davis, Nicole Maurey (mistress), Irene Worth (wife), Pamela Brown (wasted in a non-role), Annabel Bartlett (her only film), Geoffrey Keen, Noel Howlett, Peter Bull. Hamer in his penultimate film does a competent though unshowy job.

The 2012 version is good too, apparently. Not mad about the title. The film was re-edited by MGM (probably at Margaret Booth's insistence):

I have to admit that the MGM editing is brilliant in some respects as a technical exercise, but they have eliminated an important sub-plot and they have also succeeded in removing certain essential overtones which were implicit in the original story and in our version of the film. (Letter, 13 August 1959, in Robert Hamer Special Collection) (published at screenonline.)

 Music by Bronislau Kaper (an original British composed score was rejected), shot by Paul Beeson, edited by Jack Harris. MGM.