Al-muttafiq wa-l-muftariq concerns different transmitters whose own names and fathers’ names coincide in both script and pronunciation. The match may involve two individuals or a larger number; identical names do not make them one person.
For instance, if separate transmitters in different generations are both called “Aḥmad ibn Muḥammad,” merging them could distort their generation, teachers, and students. The difference is not a different spelling or vocalization but the identity of the person.
One checks each narrator’s locality, period, teachers, and pupils. These independently grounded clues preserve the distinction between individuals despite their matching names.