sumifs function exclude duplicate in one of the column

Please hellp in finding sumifs formula which exclude duplicate value in one of the column.

i want to sum 'voucher amount' (column G) subject to multiple conditions but it it should exclude duplicate document no in column B. Attached sample sheet.


Txn Code Doc No Doc Date Salesman Code Item Code Voucher No Voucher Amt Voucher Date ACPCATGNAME DIVNCODE
CRINV 2016000888 17-JAN-16 10072 100400600044 PDCRV-2015000887 29000 23-NOV-15 Commercial 10
CRINV 2016000887 17-JAN-16 10072 100400600119 PDCRV-2015000887 27720 23-NOV-15 Commercial 10
CRINV 2016000888 17-JAN-16 10072 100400600119 PDCRV-2015000887 29000 23-NOV-15 Commercial 10
CRINV 2016000884 17-JAN-16 10072 100200200006 PDCRV-2015000613 69700 31-AUG-15 Commercial 10

thanks in advance.