Double Weave is a cloth with two sides, so you have to make a warp with double the ends. One set of harnesses manage one layer and a different set of harnesses manage the 2nd layer. You thread your warp ends alternately. One end on the top layer and then thread one end on the bottom layer. So……following this idea…….if you have warped with double ends, ie a black and white end in your hand, you are all ready to thread them top, bottom, top, bottom, black, white, black, white etc. If both layers are the same yarn, you don’t need to worry about anything weaving unevenly. If one layer is a completely different yarn than the other you need to consider the rod thingme I mentioned in another post. I raise the harnesses that hold all the threads that need more tension and I separate that layer from the base layer by sliding a rod under that portion of the warp (this is all taking place behind the harnesses). I then release the tension at the front of the loom so I can slide the freshly inserted rod over the thread beam so that it is hanging at the base of the warp beam. Then I put on 3 S hooks on the rod, one on each end and one in the middle and put identical weights on them (whatever you need to take up the difference). Go back to the front of the loom and re-tension. Weave away and you will find that when you release tension to advance your warp the rod just keeps sliding down and both warps re-tension exactly the same. It is pretty cool and I do this now on all my looms regardless of 2 beams, 1 beam, 2 brakes, 1 brake…………doesn’t matter. I read about this years ago in an Ann Sutton book that is no longer in print. It works like a charm.