I’ve heard about deck crews turning off one tank of divers using independent doubles, one tank is backwards but just before you step off the boat they turn the valve the same way as the last but it’s the wrong way on the backwards tank :(
Having a buddy who knows your setup is important, my pony feeds my 2nd and my wing (BC). On decent I go to add air to my wing and my air is off (see above) I signal my daughter to turn on my air and I run my hand up the hose to the valve (I’m old and can’t reach it anymore) We all know our children never pay attention and she turns off my main tank!
Matt, did you do any penetration, I’ve seen divers roll the valve knob on the overhead.