No one tells the difference of two people who look like the same ?
Well, this Scapegoat reminds me of a movie DAVE starred by Kevin Klein and Sigourney Weaver, in which a lookalike faked to be the president of the United States for a temporary time. The other similar example is "The Assignment", with Ben Kinsley, Donald Sutherland and Aidan Quinn.
I found it hard to believe for people around the fake not able to identify the subtle differences with the real one. I mean, although they might look like the same at first sight, but if you talk to him, watch him closely enough or give him a question that he wouldn't be able to answer or respond properly, they would know "he" is not the one. Such as a mole or wrinkle in his face that the other one doesn't have, or his tone or manner or gesture or anything that would cause any suspicion.
These kind of movies just try to make the stories idealistic enough to convoy the plots, only make them unconvincingly entertaining and hard to believe.