Test 4: Validating duplicate detection...
Found 1 duplicate groups:
  - Alice Johnson: 49 duplicate(s)
WARNING: 'John Smith' has 49 duplicates, expected 2
WARNING: 'Sarah Johnson' has 49 duplicates, expected 1
WARNING: 'Michael Brown' has 49 duplicates, expected 1
WARNING: 'Jennifer Davis' has 49 duplicates, expected 1
WARNING: 'Robert Wilson' has 49 duplicates, expected 1
WARNING: 'Lisa Anderson' has 49 duplicates, expected 1

✓ All expected duplicate groups found
WARNING: Unusual match reason: 'unknown' (not in standard list)
✓ Match reasons look reasonable
SUCCESS: Duplicate detection validated!