As part of the Kashflow PayPal API import, you can ask it to automatically create invoices for customers as it reads the data from PayPal.
However, the customer billing address and shipping address are as supplied by PayPal (normally only one address is provided if any).
What should happen at this point, is that the Import APP should check if the payee is an existing customer, and if so enter that as the billing address. The shipping address provided by PayPal should then be compared and if the same, it can be ignored (instead of creating a separate shipping address).
Has anyone else spotted the bug too - if you edit the invoice, and use that to edit the customer billing address, untick the box "use different shipping address" and click on Update Customer Record - the changes ARE NOT copied across to the customer record. You have to make your changes, click on Update Customer Record, and THEN untick 'use different shipping address'