ive heard of it done, tape the two rims side by side, loosen ALL the spokes, and then transfer them in order of “left to right”ness,ie, the ones that are easy, or “on top” first, (youll go around the whole wheel, doing every 4th spoke) and then the one below it, and then the same for the other other flange.
Ive not done it, it sounds like a good way to stratch up your new rim.
I have stripped wheels down and rebuilt from existing spokes without any issues though. I would only do it with brass nipples, so if youve got aluminium nips, invest in a box of brass ones to do it with. Theyre not expensive.