If a non-fuel invoice is accidentally scanned as a purchase order you can easily convert the purchase order to a non-fuel invoice:

From the DAILY BOOKS section >> NON-FUEL INVOICES bubble >> click the PURCHASE ORDER link:

A search window will pop-up. Just click OK, as you will not have several orders in the system:

You'll see your store, click the + sign to expand to see the purchase orders.

Double Click the order to open:

Click the CONVERT TO NON-FUEL INVOICE button to convert the order into an invoice: