The same personal name may recur through successive generations of a family. A sequence such as al-Ḥasan ibn al-Ḥasan ibn al-Ḥasan ibn ʿAlī repeats al-Ḥasan but does not thereby become a scribal duplicate.
If a reader deletes a repeated name as an error, the lineage changes. If successive names are collapsed into one person, the generational structure disappears.
Rule: each ibn marks a genealogical relation. Repetition can be amended only when reliable lineage evidence shows actual copying error; repetition alone is not proof.