Hi, here is the query that worked:
SELECT "Repetition Count", "Cust. PO#", CardName, docnum, itemcode, Dscription from
(
SELECT
DISTINCT COUNT(T1."ItemCode") OVER(PARTITION BY T0."U_NBS_L_02", T1."ItemCode") AS "Repetition Count",
T0."U_NBS_L_02" as "Cust. PO#",
T0."DocNum" as docnum,
T0."CardName" as CardName,
T1."ItemCode" as itemcode,
T1."Dscription" as Dscription
FROM OPOR T0 INNER JOIN POR1 T1 ON T0."DocEntry" = T1."DocEntry"
WHERE T1."LineStatus" = 'O' AND T0."U_NBS_L_02" = T0."U_NBS_L_02") a
where "Repetition Count" > 1