Let me go back to the quantum physics. IF you want dual brakes without a "valve" DON"T test it.
If you want to solve all of this, test it, I'll supply the fluid.
I find this kind of astounding (but fun).
I already have and I had half my brakes and the car stopped and I don't have a safety valve in my car. I even drove it about 8 miles like that until I could get some brake fluid. Ron