I'm not a snake expert but what you're describing sounds like Anisocoria to me, I know because I have it. It basically just a term for unequal pupil size and and it can be caused by a bunch of things from genetics, head trauma, mild vision impairments to serious neurological disease. Sometimes its totally benign and has no impact at all, sometimes it can be indicative of something serious and life threatening.
If the difference is minimal and its been occurring since you've had them I wouldn't be too worried - usually you'd be concerned if it developed very quickly out of nowhere but it doesn't sound like thats the case. 1/5 people have Anisocoria and most are unaffected by it, I would guess its a similar case for animals but I'm not certain. Anisocoria is basically just a symptom with a broad range of possible causes so if you're worried or see any other concerning behaviours you can always give a vet a ring
Personally I wouldn't be concerned if everything else looks normal, i'd just keep an eye on it - maybe take some photos so you can compare in a couple down the track to see if the difference is pupil sizes has become more pronounced. Hope that helps, good luck!
