There are few accounts of conjoined twins from antiquity, so we tend to assume that they either didn't survive long or they were rejected or even killed as some kind of monster or bad omen. But that wasn't always the case. Leo the Deacon wrote about a set of such twins in Constantinople sometime before 944 BCE.
At this time male twins, who came from the region of Cappadocia, were wandering through many parts of the Roman Empire; I myself, who am writing these lines, have often seen them in Asia, a monstrous and novel wonder. For the various parts of their bodies were whole and complete, but their sides were attached from the armpit to the hip, uniting their bodies and combining them into one. And with the adjacent arms they embraced each other’s necks, and in the others carried staffs, on which they supported themselves as they walked. They were thirty years old and well developed physically, appearing youthful and vigorous. On long journeys they used to ride on a mule, sitting sideways on the saddle in the female fashion, and they had indescribably sweet and good dispositions. But enough about this.
Others wrote about the same twins, who were later to be the first recorded conjoined twins to be surgically separated -in order to save one twin when the other died. Read their story at Medievalists.net. -via TYWKIWDBI