Most ropes are twisted or braided. Cutting lengthwise would cut all of the threads completely destroying the rope. You could maybe unbraid the rope and deconst

Most ropes are twisted or braided. Cutting lengthwise would cut all of the threads completely destroying the rope. You could maybe unbraid the rope and deconstruct carefully into component threads and reconstruct into two ropes, Banak-Tarski(spell?) style. But that would be quite involved.