I have seen, practiced and even operationally utilized some two man movement techniques similar to these but they sometimes left me thinking about the wisdom of them.
I can see the utility in “nuts to butts drills” when used doing building clearing and other situations where you need to maneuver in tight quarters and keep a 360 deg security. Similarly I can see their advantages as immediate reaction drills where you make contact while in a stack or while approaching a scene/suspect with a partner close by.
However, once the bullets start flying I can’t see an advantage in standing close together and slugging it out. One, you present a big target and two, you fail to present the opponent with the attention dividing distraction two people can present. I would think that it would be better to split up and find cover that would allow you to mutually support each other with fire.