Bell's accounts payable clerk has a brother who is one of Bell's vendors. The brother will often invoice Bell twice for the same delivery. The accounts payable clerk removes the receiving report for the first invoice from the paid voucher file and uses it for support of payment for the duplicate invoice. The most effective procedure for preventing this activity is to: Multiple Choice use prenumbered receiving reports. mail signed checks without allowing them to be returned to the accounts payable clerk. cancel vouchers and supporting papers when payment is made. use dual signatures