If the name of a narrator, and the name of his father and grandparents are the same, however the individuals are different, then this is termed muttafiq[1] and muftariq.[2]
[1] Muttafiq means conforming in name.
[2] Muftariq means a different person. For example there is Khalīl bin Aḥmad. Likewise there were two Muḥammad bin Ya’qūb bin Yūsuf living at one time, both of whom al-Ḥākim narrates from.