Test 4: Validating duplicate detection...
Found 6 duplicate groups:
  - John Smith: 2 duplicate(s)
  - Sarah Johnson: 1 duplicate(s)
  - Michael Brown: 1 duplicate(s)
  - Jennifer Davis: 1 duplicate(s)
  - Lisa Anderson: 1 duplicate(s)
  - Thomas Clark: 1 duplicate(s)
ERROR: Expected duplicate group for 'Robert Wilson' not found

ERROR: Missing 1 expected duplicate groups