On the first time through I did have a duplicate (the error even gave me the name), but I don't have any duplicate names anymore (went in and queried the phpbb_users table and don't see any duplicates)Fatal conversion error
Fatal conversion error
functions_phpbb20.php [ 1919 ]
Colliding usernames were found on your old board. In order to complete the conversion please delete or rename these users so that there is only one user on your old board for each clean username.
Some of the names do have atypical characters (brackets, spaces, forward slashes etc.) but none of the names seem similar enough to cause a collision.