"At the beginning of time there were two brothers, twins, one named Man (*Manu, in Proto-Indo-European) and the other Twin (*Yemo). They traveled through the cosmos accompanied by a great cow. Eventually Man and Twin decided to create the world we now inhabit. To do this, Man had to sacrifice Twin (or in some versions the cow). From the parts of this sacrificed body, with the help of the sky gods (Sky Father, Storm God of War, Divine Twins), Man made the wind, the sun, the moon, the sea, earth, fire, and finally all the various kinds of people. Man became the first priest, the creator of the ritual of sacrifice that was the root of world order.

After the world was made, the sky-gods gave cattle to "Third man" (*Trito). But the cattle were treacherously stolen by a three-headed, six-eyed serpent (*Ng hi, the Proto-Indo-European root for negation). w Third man entreated the storm god to help get the cattle back. Together they went to the cave (or mountain) of the monster, killed it (or the storm god killed it alone), and freed the cattle. *Trito became the first warrior. He recovered the wealth of the people, and his gift of cattle to the priests insured that the sky gods received their share in the rising smoke of sacrificial fires. This insured that the cycle of giving between gods and humans continued."

Think it's a fascinating myth and can see how the Roman myth of its twin brothers comes into play. They reconfigured the myth from cognates and comparable mythology amongst the languages that rooted from Proto Indo European. Doesn't mean it's exact, but their reconstruction of Hittite language was closely accurate once they cracked their alphabet.