Yeah, that launch WILL pack a little punch to it, merely because it's TINY (in length).
I'd imagine having two trains launching at the same time would be impossible due to block sectioning and clearance envelopes in the tunnel.Imagine if they run a three train service on Icon on busy days and the trains launch towards each other. That will be something special.
But if the train can't get back over the top hat and immelmann once it's past, the block can be considered "clear-ish" and the next train can move onto the launch, like TTD and Kingda Ka. So the train could be launched towards you, then once it's cleared the immelmann, you can be launched. That way, if the train stalls in second half, the second launch will hold the second train, won't launch, and the system is safe.