One can possibly write a monograph or study regarding this subject: the good and bad in humanity as shown by twins in movies. It runs the gamut in films like A STOLEN LIFE, THE DARK MIRROR, THE CORSICAN BROTHERS, DEAD RINGER, COBRA WOMAN, even (watered down) in THE PRISONER OF ZENDA. In the last one, the King is a drunkard, while Rudolph Rassendyl is a brave, resourceful type (in the actual novel that is the sequel, RUPERT OF HENZAU, the King develops into a paranoid villain who loathes the distant cousin who rescued him).
As for the others, Bette Davis's good sister in A STOLEN LIFE watches her bad sister steal Glenn Ford from her. Douglas Fairbanks' wilder brother critically wounds his brother in a duel over a woman in THE CORSICAN BROTHERS. Maria Montez's good and bad sisters in COBRA WOMAN fight to the death for a royal crown. Davis good sister actually entraps herself killing the bad one in DEAD RINGER.
THE DARK MIRROR has the same split between good and bad siblings, but it makes a stab (in fitful, Freudian, Hollywood fashion) at psychoanalyzing the situation. A doctor has been murdered and the suspect is his fiancé, one Ruth Collins (Olivia De Haviland). While Lt. Stevenson (Thomas Mitchell) is questioning Ruth, and seemingly about to close a relatively simple homicide case neatly and quickly, Ruth's identical twin sister Terry shows up. It turns out that one of the two sisters was seen by dozens that night, and the other cannot produce an alibi. But the problem for Stevenson is that the one who was seen never said what her name or identity was: it could have been either Ruth or Terry. Likewise the person who was last with the Victim could have been Ruth or Terry. As Mitchell later says to the psychiatrist, Dr. Scott Elliot (Lew Ayres), unless he happens to grab the girl just after she commits the crime, there is no way to identify the guilty sister from the innocent sister once they are both back in general circulation.
Dr. Elliot is asked to examine both girls quietly. Mitchell and Elliot both are aware that this neat little alibi does not have to work permanently for the girls' advantage. You see, the innocent one does know the guilty one did it, and how long before the innocent one will crack or the guilty one will consider silencing the innocent one? Dr. Elliot studies the girls, dates both, and concludes, Ruth is normal but Terry is psychotic and jealous of her sister. Now they know who is more likely to have been the guilty one, and who the innocent one - but the innocent one still refuses to admit she is shielding the guilty one, and the guilty one (now seeing the innocent one as an impediment to her happiness with Dr. Elliot in the future) is considering how to push the innocent one over the edge into suicide.
The film as a mystery is fairly simplistic, and it's resolution is too fast. But De Haviland makes both sisters have really individual personalities that succeed as separate people. Ayres gives a decent performance trying to balance his professional detachment to his growing love and concern for Ruth. And Mitchell, although supposedly a bumbler at first, does demonstrate a crafty cat-and-mouse technique with Terry at the conclusion of the film.
As for the others, Bette Davis's good sister in A STOLEN LIFE watches her bad sister steal Glenn Ford from her. Douglas Fairbanks' wilder brother critically wounds his brother in a duel over a woman in THE CORSICAN BROTHERS. Maria Montez's good and bad sisters in COBRA WOMAN fight to the death for a royal crown. Davis good sister actually entraps herself killing the bad one in DEAD RINGER.
THE DARK MIRROR has the same split between good and bad siblings, but it makes a stab (in fitful, Freudian, Hollywood fashion) at psychoanalyzing the situation. A doctor has been murdered and the suspect is his fiancé, one Ruth Collins (Olivia De Haviland). While Lt. Stevenson (Thomas Mitchell) is questioning Ruth, and seemingly about to close a relatively simple homicide case neatly and quickly, Ruth's identical twin sister Terry shows up. It turns out that one of the two sisters was seen by dozens that night, and the other cannot produce an alibi. But the problem for Stevenson is that the one who was seen never said what her name or identity was: it could have been either Ruth or Terry. Likewise the person who was last with the Victim could have been Ruth or Terry. As Mitchell later says to the psychiatrist, Dr. Scott Elliot (Lew Ayres), unless he happens to grab the girl just after she commits the crime, there is no way to identify the guilty sister from the innocent sister once they are both back in general circulation.
Dr. Elliot is asked to examine both girls quietly. Mitchell and Elliot both are aware that this neat little alibi does not have to work permanently for the girls' advantage. You see, the innocent one does know the guilty one did it, and how long before the innocent one will crack or the guilty one will consider silencing the innocent one? Dr. Elliot studies the girls, dates both, and concludes, Ruth is normal but Terry is psychotic and jealous of her sister. Now they know who is more likely to have been the guilty one, and who the innocent one - but the innocent one still refuses to admit she is shielding the guilty one, and the guilty one (now seeing the innocent one as an impediment to her happiness with Dr. Elliot in the future) is considering how to push the innocent one over the edge into suicide.
The film as a mystery is fairly simplistic, and it's resolution is too fast. But De Haviland makes both sisters have really individual personalities that succeed as separate people. Ayres gives a decent performance trying to balance his professional detachment to his growing love and concern for Ruth. And Mitchell, although supposedly a bumbler at first, does demonstrate a crafty cat-and-mouse technique with Terry at the conclusion of the film.