In the little bios at least when I read them the other day both said "when chaos slew order" referring to her birth. I think it should be changed so that the Nightbringer one says "when order slew chaos" since then it makes sense for each iteration to exist to create balance based on which of her parents aspects gained dominion in their respective realities/timelines.
As it stands now Dawnbringer feels more canon with the event where Yasuo defeated Riven and Nightbringer doesn't really make any sense. Why would you become a being of chaos to balance a world in the influence of chaos? Especially since Nightbringer's bio suggests the world is in a state of stasis, how did it get like that if chaos won the battle of the gods?
Basically I hope it was just a typo and gets corrected since that one sentence completely cements which iteration of Soraka makes sense in existence.