This Theory is a subset of the underdress only theory. The theory goes that sometimes when the Burgundian gown is lifted in paintings you see a different colour at the hem to at the neckline. This difference is because the undergown has an applied boarder or frill on the skirt of a different fabric to the rest of the kirtle. Often the fabric shown at the hem is far richer than that shown at the neckline of the gown so this gives the wearer a way of using a very rich, expensive fabric and showing it off without using much of the fabric. Or perhaps if the hem on a kirtle wore out or became badly stained and was replaced with a different fabric. One quite often sees applied, ruffled bands of the same fabric to a kirtle, so the practice did exist.