Distribution of a bequest conditioned on the entire contents of the womb when multiple children of different genders are born?

Primary text

If the testator stated, 'If her fetus is a male, he receives two dinars, and if it is a female, she receives one dinar,' and the mother delivers both a male and a female, neither child receives anything. This is because one child is not the entirety of the fetus, nor is one child the entirety of what is in the womb. This opinion is held by the People of Opinion (Ahl al-Ra'y), the companions of Al-Shafi'i, and Abu Thawr.