The answer to this is no. However, double conditioning won't harm you either if you're doing it the right way. For instance, if you have a normal shampoo and conditioning system that you use on your color-treated hair but you have a treatment that is formulated for color-treated hair then double conditioning makes total sense. Use your regular wash and care system to cleanse and condition your hair, then use the treatment for the maintaining health of your color-treated hair.