Test 4: Validating duplicate detection...
Found 7 duplicate groups:
  - John Smith: 2 duplicate(s)
  - Sarah Johnson: 1 duplicate(s)
  - Michael Brown: 1 duplicate(s)
  - Jennifer Davis: 1 duplicate(s)
  - Robert Wilson: 1 duplicate(s)
  - Lisa Anderson: 1 duplicate(s)
  - Thomas Clark: 1 duplicate(s)

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