Wallace carries a revolver.
But the dual ammo holster on his belt behind his left hip are for autoloader pistol magazines, and not for revolver speedloaders.
At the beginning of the movie he had an autoloader pistol on and then after he took the revolver away from the old Sheriff, you see him with the revolver in his holster but whoever is in charge of art design didn't replace his magazine holster with revolver speedloaders holsters.