The fact that lifelike automatons can be made is a condition of the movie. But for me to suspend my disbelief, the process of this would have to be complicated - not something you can pull out of a hat. Even if they have the basic parts lying around, how long do you think it would take a team of special effects artists to assemble a lifelike human body?
I also maintain that if the objective of the switcharoo android was to stop the hero from revealing the villains plan to the world, wouldn't it have been easier if it had moved against him during the final showdown? Why wait? Or did some surviving baddie switch her as she was leaving the factory?
But... It's one lazily executed twist in a movie that I do not admire for its plot structural integrity anyway. To me, this movie's strengths lie entirely elsewhere, and it is for those that I enjoy it.