Certified GKH Gardening Expert
I would guess that he took cuttings from lower on the tree. Crepe Myrtles are often grafted onto hardier rootstock so as to be able to survive some climates better. The root stock will be crepe myrtle, but will be a different color. If you take cuttings from the rootstock, say suckers at the base or even the occasional shoot growing from the trunk, you will end up with a different color tree.