Musannaf Ibn Abi Shayba 13:1196

Abu Bakr narrated to us, he said: Jarir narrated to us, from Mughira, from Ibrahim, who said: If two witnesses testify that this animal belongs to so-and-so and was born in his possession, and two [other] witnesses testify that it belongs to so-and-so and was born in his possession, then it belongs to the one in whose possession it is.