We had something odd happen with our invoice back up database.

Some records (invoices) duplicated and also posted to our inventory database. 

I know when it happened, but am not sure how it happened.

This is how our system works.

One database is used for processing invoices.
1. At the end of the day the sales are exported in a text form to the back up database.
2. The files are then imported into a backup database along with text files from other locations. 
3. The imported records are posted to the inventory each day.
*** At the end of each week, I create a backup database for the invoices and the inventory labelled the date I saved them.

Duplicates appear in the database after the November 13th backup and before the November 22nd backup, but duplicates were not from that date range.  I have attached an example of the reports from each database.  This invoice was from September 24th 2021.