okay now info: in other animals the term for this is called heterochromia. in other animals, it can be inherited or it is the effect of random genetic fun-times. since your snake already exhibits some genetic fun-times (see: paradox markings) i would suspect it comes from that same anomoly.
EDIT: in other animals, this (heterochromia) is common for chimeras. you may have a chimera!!!
It also occurs sometimes in humans as well actually. Tim McIlrath of the band Rise Against has heterochromia...one of my favorite teenage bands when I was in the "rebel" stage lmao.