Shock news: Actors are people, and they sometimes get on with other people and sometimes they don’t! Being on a film set involves hours of hanging about with others on the set, including other cast, stunt people, directors and ADs and sometimes SAs. You quickly get to know the people you like chatting to in that downtime.
One of my favourite photos of a star hanging out with her stunt doubles is this one: the wonderful Karen Gillen with her stunt doubles onvthe set of Jumanji: Welcome to the Jungle. The outrageously misogynist outfits have nothing to do with it of course!