About 5 years ago i sold off a clump of unknown pink daylily and planted a new cultivar where the pink one was. Last year when the new one was blooming i noticed on of its scapes had a pink bloom and it was down low and shooting out from the side. So some of the pink got left behind but it was such a small amount of root that it took 4 years to mature into a fan,scape and bloom.
Sometimes when you think you got it all nature surprises you. Blue06, ditch the ditch lily. It will only suck nutrients and water and compete with your beautiful red one.