Tons of variables to consider.
With one side longer, than can make a difference. This can happen when using two colors and one color is thicker. This is because the coloring process these days isn't a dye, but rather a coating. Colors don't bleed anything close to what they used to do, but with some colors the coating is a tad thicker so you can get uneven bundle tension if you aren't careful. The easy fix is to pay attention when making the second loop and, if needed, put a tiny bit extra twist in the longer bundle to take up the excess.
Ballooning is usually only a problem with endless. That's why you put some twists even in an endless string.
As to the noise, that is probably at least part of it, but there could be lots of other reasons. Hard to say from a computer. If there is no counter-twist, that could also be adding to the noise.