I think you are not trying to understand what your query is doing! just put whatever column you want in your select clause!!

SELECT CASE WHEN RowCnt > 1 THEN

CONVERT(varchar, WO) + '(' + CHAR(96 + Row_no) + ') '

ELSE CONVERT(varchar, WO) END, RD FROM

(Select * ,

Row_Number() OVER (Partition BY WO ORDER BY WO) as Row_No

FROM #WO) #t1

INNER JOIN (SELECT wo AS Wo1,COUNT(*) AS RowCnt FROM #wo GROUP BY WO) a

ON #t1.WO = a.wo1