What is the ruling if ownership is ruled not to have transferred to the buyer, and both the buyer and seller attempt to manumit the slave?

Primary text

If we adopt the other narration, holding that ownership did not transfer to the buyer, the manumission of the seller is effective, while the buyer's manumission is ineffective. If both the seller and the buyer manumit the slave, and the buyer's manumission precedes the seller's, the ruling follows what has already been established. If the seller's manumission precedes the buyer's, then neither manumission should be effective. This is because the seller's manumission was ineffective as he manumitted property he did not own, but his manumission served to rescind the sale and reclaim the slave, preventing the buyer's manumission from taking effect. If the seller repeats the manumission a second time, his manumission becomes effective because ownership has returned to him, resembling a situation where he reclaims the slave using explicit declaration.