Test 4: Validating duplicate detection...
Found 0 duplicate groups:
ERROR: Expected duplicate group for 'John Smith' not found
ERROR: Expected duplicate group for 'Sarah Johnson' not found
ERROR: Expected duplicate group for 'Michael Brown' not found
ERROR: Expected duplicate group for 'Jennifer Davis' not found
ERROR: Expected duplicate group for 'Robert Wilson' not found
ERROR: Expected duplicate group for 'Lisa Anderson' not found

ERROR: Missing 6 expected duplicate groups