"According to a scholar named "Chrystos", the multiverse was originally nothing but swirling Chaos. Gods slowly formed in the primal confusion, and among them formed the greatest of Law's champions, the Twin Serpents Jazirian and Ahriman. In the beginning they were intimately intertwined with one another, Jazirian's tail in Ahriman's mouth and vice versa. Together they established the fundamental principles of the planes: the Unity of Rings, the Rule of Threes, and the Center of All, creating the ring-shape of the cosmos, the triads that dominated it, and the plane of neutrality called the Concordant Opposition or the Outlands.
Ahriman and Jazirian, who originally worked together in all things, warred over which plane would be the center of everything. Ahriman chose Baator and Jazirian chose Heaven. They struggled so greatly that, with their tails still in one another's mouths, they forcibly tore apart. The blood from Jazirian's damaged tail formed the first couatls, while the blood of Ahriman, whose terrible fall created a vast pit called the Serpent's Trench, formed the first pit fiends. Ahriman, wounded and imprisoned by the laws he himself created, went by the guise of the archfiend Asmodeus, while Jazirian remained quietly in the background, using her couatls to gather intelligence on Ahriman's goals."
Whenever something begins with, "According to a scholar..." it is not set in stone. Is Jazirian the god of coatls? Sure. Did he originate them? That's iffy. It's essentially up to the DM to decide if it's true or not. We don't have a situation where there are two canon origins. We have a situation where canon is unclear and there are two possibilities. At least early on in D&D. If it became more solid after that, I don't know.
