On purlwise's blog, she asks: I have a painted roving; if I make it into 2-ply sock yarn will the colors look ok?
Or, if splitting the length doesn't float your boat, you could find the repeat in the dye on the roving and split it there, instead.Alternatively, consider Navajo plying to preserve the color changes.
I'll try to dig my pair of fingerless gloves out of my sample-bucket for a photo shoot; one is a 2-ply done as described here, and one is a Navajo ply. All you have to do to confirm the adage that a 3-ply is rounder yarn and a 2-ply is flatter yarn, is put these on. The Navajo (3) ply is squisher/firmer, the 2-ply is flatter against the hand. And actually, in gloves, flatter against the hand is a good thing between the fingers!