A simul rappel is when two people rappel down opposite ends of the rope.
To set up a simul rappel:
This setup allows you to rappel single strand with no blocks or knots.
The anchor must be very strong for a simul rappel. This setup applies approximately 1.5 times the normal force to the anchor when the rappelers take turns and approximately 2.0 times the normal force when the rappellers go down together.