Suppose one chain names a narrator as “al-Baṣrī” and another as “al-Kūfī.” This alone does not prove two different individuals: someone may have originated in one town and settled in another. Equally, the two labels must not automatically be merged without evidence.
Method: compare full name and lineage, teachers, pupils, travel dates, birth and death, and known residences. The inquiry then establishes whether two chains refer to one transmitter or to different namesakes.
The purpose is to prevent conflation of identities—either importing one person’s biographical judgment into another’s record or fragmenting a single narrator into fictitious persons.