Also question is, what does it mean when actors have a double?
double-casting
Likewise, how do movies do double acting? Unlike a traditional acting situation, a star is required to act with a body double who stands in place of the actor's other character. Once they film the first scene, they quickly change from one character to the next and then reenact the scene as the other character.
Similarly one may ask, do actors have doubles?
In addition to stunt performers, most movies employ body doubles (or photo doubles) with a passing resemblance to the principal actors.
What is the difference between a stand in and a double?
A stand-in is any person who is used to replace lead actors and stars for tedious parts of filmmaking. Stand-ins do not show their face or have their voice in the final film. A double is someone who is used in place of a cast member where the real actor cannot be used because of danger or other reasons.