I saw it in the 2000s. It's about a man who is arrested multiple times for attacking and abducting women. The victims recognise him during 'police lineup' ... multiple accusations, the police is watching him. So his life is ruined. At the end of the film however -during another attack against a woman - he has a perfect alibi: he has witnesses of him being somewhere else, and he passes the polygraph test. To solve the mistery, the detectives bring the latest victim to a house she remembers from the attack. There an uknown man opens the door who doesn't know anything, but when the detective shows him the photo of our man, the guy notes he totally looks like his own brother!
That's the twist: Our hero was innocent, while the real criminal looked like just like him! A doppleganger. The police gets the address and storms the real criminal who is arrested. Our hero is vindicated. In the last scene, the newspapers show the pictures of the two man on the front page, they look like twins...
Ps: I think the protagonist had a mustache.
Can't remember that film's name? Post the plot, and see if other users can help.