It's not entirely uncommon for actors to play two roles in one movie. We've seen single actors play identical twins before. Frequently, the difficulty in playing two roles can be in finding ways to make the two characters look and feel different. Apparently, Will Smith found the difference between the characters of Henry and Junior in the walk. Specifically, it came from the fact that Junior walks in a very specific way, like he's never had sex.
In an interview that Will Smith posted to his Instagram account, he revealed that the secret to playing his younger self was to walk as if his glutes were tighter, apparently, implying the character had never had sex.
The secret to my performance in Gemini Man? Mastering how to walk like a virgin. It’s all in the glutes.
The idea that Junior, the clone Will Smith, is still a virgin isn't something entirely created by Smith. There's actually a moment in the film where Henry suggests that to be the case. Since Junior has been raised to become a perfect machine for assassination, he hasn't had much opportunity to socialize. Henry implies that he has had this issue as well, which is part of how he knows Junior's situation.
While I can't say I noticed that Will Smith walks particularly differently when playing his two different characters, it's certainly possible that he does. It's certainly not the craziest idea. One can very easily tell which version of Will Smith you're looking at without having to see everything so clearly. And since, large portions of the movie take place at night, and the CGI can get a bit wonky at times, all the little touches like this only help the movie overall.
Of course, it's questionable how many people actually saw the work that Will Smith put into his various walks. Gemini Man opened at the box office in third place behind the second weekend of Joker as well as the newly released Addams Family. It made just over $20 million, which, considering how much the movie cost to make, isn't going to make the studio too happy. We'll have to wait and see how the international box office shakes out to see if it is able to embrace Gemini Man any better.
Check out Will Smith's full comments in his post below.
Gemini Man is in theaters now.