Imagine a scenario, I use beam target engines to stop the opponent, and my phaser beams also roll a proc. Is the engine subystem in the avilable pool of subsystems to disable? Is the disable extended? or does the proc roll again? or does the code just silently exit on failure? or what?
In the general case, it currently works the same way two Holds or two Disables would work - the first Offline can expire while the second Offline is still present, leaving the system offline until the second proc also expires. Most of our crowd control abilities have Resistance to re-application included when they wear off - this is intended to reduce the duration of chained CC's. There may be some powers out there that won't apply their control if the target is already controlled, but that's not a general rule that we have set up.
Jeff "Adjudicator Hawk" Hamilton
Systems Designer - Cryptic Studios