Test 4: Validating duplicate detection...
Found 5 duplicate groups:
  - John Smith: 0 duplicate(s)
  - Sarah Johnson: 0 duplicate(s)
  - Michael Brown: 1 duplicate(s)
  - Robert Wilson: 0 duplicate(s)
  - Thomas Clark: 1 duplicate(s)
WARNING: 'John Smith' has 0 duplicates, expected 2
WARNING: 'Sarah Johnson' has 0 duplicates, expected 1
ERROR: Expected duplicate group for 'Jennifer Davis' not found
WARNING: 'Robert Wilson' has 0 duplicates, expected 1
ERROR: Expected duplicate group for 'Lisa Anderson' not found

ERROR: Missing 2 expected duplicate groups