Various fields or combination of fields may be used to test for duplicate records. The
auditor, however, needs to understand the relationship between the files to draw meaningful
conclusions from the test results. For instance, in our example each disbursement
voucher is issued in payment of a single supplier’s invoice, and each supplier invoice relates
to a single purchase order. Recognizing this relationship, the auditor can conclude
that the same PO Number value should not normally exist in two or more records in the
Disbursement Voucher file. A search for duplicate records in the file produces the report
in Figure 10.13.