can you run 2 pistons of one solenoid legally?

[Kevin Sevcik]

Sure, there's no rule against it, just a rule against using multiple solenoid valves to drive one cylinder.

[IndySam]

Yes but you will decease the air flow to the two cylinders in half. That may not matter for smaller cylinders but it will make larger ones slow.

[Curt Henderson]

Another issue to consider is that the cylinders will extend and retract in a staggard pattern due to only one cylinder moving at a time due to imbalance if the air pressure in the system which will move the cylinder with the least amount of resistance first. If they are hooked to a rigid enough structure that affect will be minimal, but in a flexible(less rigid) structure it could get bound up and not move after the first cylinder extends.