If a man has two wives, the one beloved and the one hated, and they bear him sons, the beloved and the hated, and the firstborn son is the hated one’s—
English: “The firstborn son” — the son, and not a tumtum or androginos; the firstborn, and not a case of doubt.
On the daf / in context: When two wives give birth at the same time and it is unknown which child emerged first, neither is treated as the firstborn for the double portion. If the children were later mixed, they write mutual authorizations and claim the bechorah together from the ordinary heirs.
Type of Learning
Mi’ut excluding tumtum, androginos, and cases of safek.
What Is Learned
Neither a tumtum/androginos nor a child of doubtful priority receives the double portion of the firstborn.