If you're importing Sales, you have the option to reject duplicate transactions or add them to your company file. Each sale is checked for duplicates according to the setting of the preference Warn for Duplicate Invoice Numbers in the Preferences window. (Preferences window -- Sales view)
In the Preferences window, you can choose to warn for duplicate invoice numbers only, customer PO numbers only or either duplicate invoice numbers or duplicate customer PO numbers; you can also choose to leave the preference unmarked.
If you mark the preference, each sale will be checked for duplicates according to your selection when you import sales:
If you leave the preference unmarked, 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.
Note: Using the field: Identify xxx by