An unqualified or unspecified narrator (muhmal) is someone mentioned in a chain without enough particulars to choose among plausible individuals—for example, “Aḥmad” when a teacher had more than one pupil of that name. Muttafiq wa-muftariq is the underlying phenomenon of distinct people bearing matching identifying names.
The subjects overlap but are not identical. Studying namesakes helps resolve an abbreviated reference; teachers, pupils, cities, and the rest of the chain then identify the intended person.
Method: preserve the exact wording in the isnād, list possible individuals, and test them against transmission connections. Do not assign a definitive biographical ruling before a supported identification is reached.