It is the most cost effective may to make the rule. NOT the best idea BUT it does work.
You are correct I had a discussion with tech at VIR this year and that is the rule. Now I am not aware of any updates u may want to ck.."Dual rear brakes may also use one caliper as long as
the calipers are connected to separate master cylinders and the caliper sides are not hydraulically connected to each other."
I thought.it was two calipers, 2 master cylinders, and one rotor minimum?
Actually I set them up to get about as much equal braking as possible. I don't know of anyone who would pull back the second set of pads. There may be some that do, but I wouldn't. You have to remember road racing speeds are a lot higher than sprint tracks.It's no better (or worse) than setting that 2nd full caliper up so that it never really grabs so you don't have extra parasitic drag -- and don't tell me people don't do that.