I don't believe you can do double sided manes as they don't have a "left" and "right".
This may help you figure out color placement though to give it the appearance of being double sided!
https://www.deviantart.com/northernred/art/FeralHeart-MANE-tricks-tutorial-Canine-part-514907588
Locking this as your question has been answered. Thank you Bloo~