Greek names were very common among slaves and freedmen and Daphnus is one such example. The two Publii Vibii (doubling the letter - PP - is normal where two of anything are concerned) were probably brothers, with the same praenomen Publius (and nomen Vibius), but different cognomina (not mentioned here). For two brothers to have the same praenomen was perfectly acceptable, and their father will probably have had the same praenomen. 'Publius' will have been passed down to at least one of their descendants and all of their freed slaves. On the funerary inscriptions of freedmen, the praenomen of the patron is given just as the praenomen of the father would be given (filiation) for free born men.