[Argess]

Here's what accounts for the opposing forces: The caliper with piston(s) on only one side SLIDES. That's what puts pressure on the pad that doesn't have a piston behind it.

I work out brake torque finding the drag from one pad, then double it to find the total brake torque. If you use piston area of both sides, you don't double it.

There is no difference in brake torque between a caliper with 2 pistons per side and one with only 2 pistons on one side.