Try a duplicate-ID and missing-value check — Small Data Clinic

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Submit this sample with required columns member_id,name and identifier member_id:
member_id,name
0012,Ari
0012,Bea
0013,
Expected structural findings: duplicate 0012 and a blank name in the final data row. Keep IDs as text. The diagnostic cannot decide whether Ari and Bea are the same person or which row is authoritative. Do not merge names automatically.

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