Test 4: Validating duplicate detection...
Found 7 duplicate groups:
  - Frank Brown: 1 duplicate(s)
  - John Smith: 2 duplicate(s)
  - Sarah Johnson: 1 duplicate(s)
  - Jennifer Davis: 1 duplicate(s)
  - Robert Wilson: 1 duplicate(s)
  - Lisa Anderson: 1 duplicate(s)
  - Thomas Clark: 1 duplicate(s)
ERROR: Expected duplicate group for 'Michael Brown' not found

ERROR: Missing 1 expected duplicate groups