I have just been reading this which is admittedly very old, and there is a statement which has me totally confused.
... the master might disregard the regular form and give the freedman any name he pleased. Thus, when Cicero manumitted his slaves Tiro and Dionysius, he called the former, in strict accord with custom, Mārcus Tullius Tīrō, but to the latter he gave his own praenōmen and the nōmen of his friend Titus Pomponius Atticus, the new name being Mārcus Pompōnius Dionysius.
I do not understand how Cicero could give his freedman the nomen of another. My understanding was that in formal contexts, Tiro, for example, would be M. Tullius Tiro l M - eg Marcus Tullius Tiro, freedman of Marcus - which would indicate a clear identity and affiliation. How would Mārcus Pompōnius Dionysius do this?
(If this would be better suited to the Latin Language forum, please let me know.)
Also posted on Latin Language site - https://latin.stackexchange.com/questions/1985/confusion-re-the-naming-of-roman-freedman