The way the energy is transfered from the weapon to the body could be different and cause the weapon to jerk around more than usual. That could be called increased recoil even though the amount of energy doesn't increase by much.
The energy is the same when you shot a gun properly braced or shot it from the hip, but the later is still much harder to control. Force isn't everything when it comes to recoil and physics doesn't always scale in a linear way.