Ideally you should be placing and spacing pro such that both ropes catch you. Ie, you fall off 10m above pro 1 and 11m above pro 2, and come to a stop 10m below pro 1 and 9m below pro 2 with the force of the fall distributed 55%-45% on the two pieces.
The only way this will not work is if your pro is spaced such that you fall and end up above the pro on one rope but below it on the other. Then all the force ends up on the one rope where you are below the pro.