«هَذَا لِفُلَانٍ» ... «مَا كَانَ لِي قَطُّ وَلَكِنَّهُ لِفُلَانٍ آخَرَ»
“This belongs to one person ... but to another person.”
A statement assigning the same slave to one person and then to another creates conflicting claims. Whether the speech is continuous or separated, and whether the first admission has already established a legally recognized claim, matters.
The later wording does not automatically extinguish the first person's established right. The source analyzes the two claims according to the structure of the utterance and the rule governing admissions.