Is it permissible to divide a vow between two people who live in the same house, when both of them made the same vow?

If two people make vows regarding two separate things, it is not permissible to offer one thing in place of both. Rather, each of them must fulfill their vow completely, for the Prophet, peace and blessings be upon him, said: "Whoever vows to obey Allah, let him obey Him." However, if each of them vows half of a single thing, then it is permissible to offer one thing, considering half of it from one person and the other half from the other.