Something like this?
SELECT x.id
, DENSE_RANK() OVER (ORDER BY x.id) as DenseRnk
FROM
(SELECT 'A123' AS ID
UNION ALL
SELECT 'A124'
UNION ALL
SELECT 'A124'
UNION ALL
SELECT 'A123'
UNION ALL
SELECT 'A127') x
And then do like Phil said and join back to the original table to show where to put each item?