Horrible idea. The worst part is that you're using it instead of a proper method of marking.
You will exceed your conduit fill in a heartbeat since instead of n wires of x diameter, you now have n/2 (effective wires) of 2x diameter.
Becuase it's irregular, your AHJ is likely to nix it and make you tear it out.
You may also have problems with thermal limits in NEC 310.15. That calculation assumes that 10 feet of conduit with 6 wires contains 60 feet of wires. Twisting adds length, so you might actually have 70 feet of wire in your 10 feet, counting as 7 conductors for 310.15 purposes.
Have you ever added a wire to existing conduit? This would make it a lot harder, because all those twists will create hundreds of snag points.
Unless you twist them so tight as to damage the wire, they're going to fray anyway once you get into the box. You won't tell them apart without other marking, which is really what you ought to be doing.
Mark individual wires to make them distinct. Allowing two identical, undistinguishable wires into the same conduit is planning to fail unless they are messengers or phases.**
That's why they make 11 colors of wire and 10 colors of tape. (11 if you count "no tape" as a tape color). 121 combos and you only need 8.
** But even that can be screwed up: One non-electrician ran 2 conduits to our machine shop, great, except he put all the 10AWG wires, 4 red and 4 black, in the same conduit. And then, he picked 1 red and 1 black to be circuit 1! shakes head If he had just put 2x2 in each conduit, and use both blacks in conduit 1 for circuit 1, he would have accomplished all his marking requirements with no tape. Not that hard if you use your thinking cap.