Muhammad bin Abd al-Rahman bin Thawban (may Allah have mercy on him) says that a man asked Ibn Umar (may Allah be pleased with them both) about a slave half of whom had been freed. He said: The rulings for slaves apply to him until he is freed completely.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب العتق / 21365
Ibn Tawus (may Allah have mercy on him) narrates from his father concerning a man who died while half of him was free; he said: "It is to be divided between the two of them in halves: half for the one who freed him and half for the one who did not free him."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب العتق / 21366