Test 4: Validating duplicate detection...
Found 9 duplicate groups:
  - John Smith: 2 duplicate(s)
  - J. Smith: 2 duplicate(s)
  - Sarah Johnson: 2 duplicate(s)
  - Michael Brown: 1 duplicate(s)
  - M. Brown: 1 duplicate(s)
  - Jennifer Davis: 2 duplicate(s)
  - Lisa Anderson: 2 duplicate(s)
  - Thomas Clark: 1 duplicate(s)
  - T. Clark: 1 duplicate(s)
WARNING: 'Sarah Johnson' has 2 duplicates, expected 1
WARNING: 'Jennifer Davis' has 2 duplicates, expected 1
ERROR: Expected duplicate group for 'Robert Wilson' not found
WARNING: 'Lisa Anderson' has 2 duplicates, expected 1

ERROR: Missing 1 expected duplicate groups