The first sketch below shows a two Pulley arrangement to achieve a 2:1 mechanical advantage for Pyramid stone lifting, in lieu of a single pull rope.
Sketch 2 is a close-up of the second Pulley in Sketch 1.
Sketch 3 illustrates an arrangement of Pulleys for 2:1 mechanical advantage for use in Pyramid stone moving -- cutting the number of pullers required by 50%. A simple mechanism supporting the two Pulleys could be readily moved from stone to stone. Such a Pulley arrangement would have been obvious to the Pyramid builders based on Lehner's illustration of the pulley system in the Great Pyramid (to foil tomb robbers) in his book, The Complete Pyramids (page 113).
The fourth sketch shows a cross section of an obelisk lift technique using "opposed" Egyptian Pulleys.