Avoiding duplication in report in OBIEE 11g

Avoiding duplication in report

SUM(CASE WHEN EVALUATE_ANALYTIC('row_number() over(partition by %1 order by %1 )' AS INT,"Sales - CRM Orders"."Order - Other Fields"."KPNBR4 KPN Order Number")=1 THEN "Sales - CRM Orders"."Order Item Attributes"."Net Price" else null end by "Sales - CRM Orders"."Order - Other Fields"."KPNBR4 KPN Order Number")