If you're importing Sales, you have the option to reject duplicate transactions or add them to your company file. (How to handle duplicate records when importing) Each sale is checked for duplicates according to your selection in the Preferences window. (Preferences window -- Sales view)
In this window, you can choose to warn for:
or
When you import sales, each sale will be checked for duplicates according to your selection.
If you've marked the preference Warn for Duplicate Invoice Numbers, imported sales will be checked for duplicated invoice numbers only. If you've marked the preference Warn for Duplicate Customer PO Numbers, your imported sales will be checked for duplicate customer PO numbers only. If you've marked the preference Warn for Duplicate Invoice and Customer PO Numbers, your imported sales will be checked for either a duplicate invoice number or a duplicate customer PO number.
If you haven't marked the preference, each sale will be checked for either a duplicate invoice number or a duplicate Customer PO number; that is, your imported sales will be checked as if you had selected Warn for Duplicate Invoice and Customer PO Numbers on Recorded Sales in the Preferences window.
If the Invoice or Customer PO field is blank, the field is not considered a duplicate.
If you choose to reject duplicate records, the information that's rejected will be placed in the Import Log report, which is created at the time you import.