They are effectively two pistons in line using one fluid reservoir not as used to be the case with two seperate reservoirs & pistons on some cars.
I guess if the seal fails in one you lose one side & if it leaks the fluid can run out affecting both circuits. I would have thought before that the driver would notice.
If you are really unlucky the seals on both pistons could fail. I also thought in the CX case that the casting was porous so pressure would leak and not drive the brake calipers.
But having driven several P4s and one P6 I found the brakes very poor with a long travel and little feel.
JohnV6 2022 CX Plus Four 2025 MG ZS EV aka Trigger
