Whats the meaning of Tirmidhi 1547

The hadith: > Abu Umamah, and other than him from the Companions of the Prophet (ﷺ), narrated that the Prophet (ﷺ) said: "Any Muslim man who frees a Muslim man, then it is his salvation from the Fire - each of his limbs suffices for a limb of himself. And any Muslim man that frees two Muslim women, then are his salvation from the Fire - each of their limbs suffices for a limb of himself. And any Muslim woman that frees a Muslim woman, then she is her salvation from the Fire - each of her limb suffices for a limb of herself." My question is, whats the reason that freeing 2 Muslim female slaves is equivalent to 1 male if a man frees them, but for a Muslim woman freeing 1 Muslim female is enough?