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

ERROR: Missing 2 expected duplicate groups