I would ask for a better picture, taken in a well lit room and preferably without flash !
I think the flash hits the snake on the left more and reflects off of her, possibly just washing out her color a bit ?
Outdoor pictures would be best, but I know its not do-able for many, yet !
But definitely a picture a bright room without flash, both snakes next to each other.
Going by the picture you have, I would pick the one on the left. It might not be a whole lot lighter without the flash bouncing off of it, but I definitely like the head marking. Just something about that one...