What is the consequence of mutual oath-taking (Tahaluf) in a dispute over the manumission amount after the slave has been freed?

Primary text

Those who hold that mutual oath-taking is required state that if they take oaths, either party may nullify the manumission unless one accepts the statement of the other. If the mutual oath-taking occurs after manumission, the freedom cannot be revoked because it cannot be undone once established. Instead, the master is compensated for the value of the slave, and the slave receives back what he paid. If the payment and value are of the same kind, they offset each other up to the lesser amount, and the party with the greater amount receives the surplus.