MySQL 8.0

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CREATE TABLE tablename (
  `disposition` VARCHAR(9),
  `uniqueid` DECIMAL(20, 5)
);

INSERT INTO tablename
  (`disposition`, `uniqueid`)
VALUES
  ('ANSWERED', '1595409523.22546'),
  ('NO ANSWER', '1595409523.22546'),
  ('BUSY', '1595409523.22546'),
  ('BUSY', '1595406475.22391'),
  ('NO ANSWER', '1595406475.22391'),
  ('BUSY', '1595406475.22391');
select t.disposition, t.uniqueid
from (
  select *,
    row_number() over (partition by uniqueid 
                       order by field(disposition, 'ANSWERED', 'NO ANSWER', 'BUSY')) rn
  from tablename                                    
) t
where t.rn = 1


disposition
uniqueid


NO ANSWER
1595406475.22391

ANSWERED
1595409523.22546


select case 1
         when max(disposition = 'ANSWERED') then 'ANSWERED'
         when max(disposition = 'NO ANSWER') then 'NO ANSWER'
         when max(disposition = 'BUSY') then 'BUSY' 
       end disposition,
       uniqueid  
from tablename
group by uniqueid


disposition
uniqueid


ANSWERED
1595409523.22546

NO ANSWER
1595406475.22391