Test 4: Validating duplicate detection...
Found 10 duplicate groups:
  - J. Smith: 2 duplicate(s)
  - John Smith: 0 duplicate(s)
  - Sarah Johnson: 1 duplicate(s)
  - M. Brown: 0 duplicate(s)
  - Michael Brown: 0 duplicate(s)
  - Jennifer Davis: 1 duplicate(s)
  - Robert Wilson: 0 duplicate(s)
  - Lisa Anderson: 1 duplicate(s)
  - T. Clark: 0 duplicate(s)
  - Thomas Clark: 0 duplicate(s)
WARNING: 'Michael Brown' has 0 duplicates, expected 1
WARNING: 'Robert Wilson' has 0 duplicates, expected 1

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