When you set up PayPal you’re asked to set a start date for when you would like to start importing transactions from. As you import, this date changes based on the date and time if the last import. If you would like to import transactions from the past you need to change this start date.
Changing the Start Date
To change the start date go to Dashboard > Click the Pen Icon under Imports to bring you to the PayPal settings page. Under General Settings, change the Start Date to a date in the past followed by clicking Update & Re-import.
If you had already converted PayPal transactions from the staging area, these need to be deleted first as otherwise they would be brought in again as duplicates.