Honestly, if you hadn't done so much due diligence regarding the possibility of a reroot, from the pictures alone I'd assume that was the case just because it looks so odd (the hair itself, not just the colour, with the two next to each other like that). And she was only out in one year, at the end of production...so it would be odd for her to have a variation in hair shade?
But it looks so evenly coloured, that fading seems unlikely?
Mystery.
Did notice her symbol seems slightly fainter though...dunno if that means anything. Also her eye paint is a bit bolder? So maybe it is a batch thing?
Nurses are really htf here so I have never had doubles of any of them, but I am pretty sure mine looks like your normal one. I'll have to check.