Why do people use two guns at once in movies?

I think this is partly related to the way holstering a weapon is portrayed in media, where the character often just shoves the gun in their holster. I imagine that the logic behind using two guns at once is that it’s easier to just switch guns than to reload and switch magazines. But I’m just curious to know why this became a thing in movies and TV shows.<br><br>Edit: I’m talking about action movies with pistol caliber guns like in John Wick or movies with hand-held machine guns. Not hunting or sport shooting.