SELECT  DISTINCT
*
FROM Tarefa T
WHERE
T.TarID in(select TarID from Tarefa where T.TarTitulo = 'Bloquear Cliente - Inadimplente' AND T.TarTipID = 572
and T.TarID not in (select TarID from Tarefa where TarTipID = 574 and TarTitulo = 'Desbloqueio Cliente'))