PSI measures Pounds per Square Inch(P.S.I), thus meaning that both of those are correct.

If you have two, one filled with 100 PSI, and the other with 50 PSI and you connect them with a tube, they will level to 75 PSI. What it does is that it averages the two of them to level them out.

I don’t know if that made sense, but basically the answer is that the question logically doesn’t make sense.

If you were to put 50 PSI into both reservoirs, then one is filled with 50 PSI, and the other is filled with 50 PSI. If you put 100 PSI into both reservoirs, then one is filled with 100 PSI, and the other is filled with PSI.

PSI is just pounds per square inch, and that means that doubling both pounds and inches will still be the same exact PSI.

For Example; if you were to have 1 pound per 2 square inches(1/2), and you double the pounds and the inches, you will get 2 pounds per 4 square inches(2/4). So… Is 1/2 the same as 2/4?

If this still doesn’t make sense, I’ll explain more.

This has been answered

The system may only be charged to 100psi. You may charge each tank to 100psi. And the pressure in the system will be 100psi.