It’s this idea that a pre-rigged device definitively fixes both strands of the rope at the anchor that requires more thought. With most ropes and devices, this seems to work – but aikibujin was monkeying with this technique and decided to test out the scenario in which the first rappeller, still tied into his end of the rope (because he was the leader of the last pitch), descends both strands of the rope, but then accidentally rappels off the unknotted strand. At this point his full weight comes onto the strand to which he’s tied.