stand-in, double, understudy
Il est la doublure de ce personnage.
He is the understudy for this character.
Vous l'avez choisie comme doublure ?
Did you choose her as a stand-in?
Non, c'est ma doublure cascade, Cliff Booth.
No, this is my stunt double, Cliff Booth.
— Once Upon a Time... in Hollywood (2019)
Voici le monsieur qui fera la doublure d’Alexandre.
This is the man who will be Alexandre’s body double.
— La Nuit américaine (1973)
There is always a lining.