Corporate losses from multiple payments to vendors for the same merchandise have
been estimated to be in the hundreds of millions of dollars per year. Malfunctioning
computer programs, data entry errors, and the failure of authorization controls are usually
the basis for duplicate payments. Occasionally, however, they are the result of dishonest
vendors who attempt to circumvent internal controls by sending two supplier
invoices with different invoice numbers for the same purchase. Sometimes they send
multiple copies of the same invoice or simply add a letter behind one of the invoice
numbers to differentiate them. The auditor can test for duplicate records in a large file
by employing ACL’s Duplicate feature. This technique is demonstrated below using the
Disbursement Voucher file in Table 10.5.