The coincidence can extend beyond name and father to grandfather, kunya, nisbah, or other identifying features. A more complete apparent match does not necessarily ease identification: it can make a false merger more tempting.
Worked case: Two narrators have the same name, father, and kunya. One heard from a teacher in Basra, while the other was born after that teacher died. This chronological impossibility proves they cannot be one person despite matching labels.
Rule: shared names warrant an inference of shared identity only when independent chronological and isnād evidence supports it. Resemblance by itself is not sufficient for assessing narrators.