Nafi' (may Allah have mercy on him) said that Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) had two slave-women who were sisters, and he had intercourse with one of them. Then he intended to have intercourse with the other, so he removed the one with whom he had had intercourse from his ownership.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13939