I am totally convinced there is more than 1 “NOT JOE’s”
It is done so we don’t pick up on the subtle differences. It is always morphing a bit.
Multiple doubles to blur things is intriguing...makes sense. The film THE DEVILS DOUBLE touched on this re: Sadam Hussein. It is a really cool movie, good acting, action, but falls off at the end. Worth watching.
https://www.youtube.com/watch?v=2-MsGEWFiYg