Dual vs. single master

[70 LS1]

Had a couple of questions on dual vs single master cylinders.

I was looking over a stoptech article and saw that the balance bar splits the pedal force going to the masters. For example if 600 lbs force is applied by the pedal to the balance bar and the bar is setup in the center then each master will have 300lbs force on them. Now if each master has a 1 square inch area, then both front and rear lines will have 300psi. Makes sense.

I think my confusion comes from the single tandem master cylinder. Lets say you have the same 600lbs applied by the pedal to the master cylinder and you still have the 1 square inch of area. Does that mean you have 600psi in the front and rear lines? Or do the two internal pistons of the master split the force giving you the same 300psi?