Попробуйте это:
create table Tbl(UniqueValue char(8), Remarks char(3));
insert into Tbl values
('URTA-144', 'ACC'),
('URTA-144', 'ADD'),
('URTA-144', 'ADT'),
('URTA-145', 'ALL'),
('URTA-145', 'ALL'),
('URTA-145', 'ALL');
select UniqueValue from Tbl
group by UniqueValue
having count(distinct Remarks) = 1;