Reasonable. This is an example of what I mean.
Here's Priyanka Chopra with her replacement actress, Aja Frary:
Here's Chris Hemsworth with his stunt double, Bobby Holland Hanton:
Here's Ben Affleck with his replacement actor, Rich Cetrone:
Here's Reese Witherspoon with her replacement actress, Marilee Lessley:
As you can see from this example, they don't look exactly the same, but they're good enough to fool the camera.