When you goto pay for the item with PAYPAL, it tells you the item has ALREADY BEEN PAID FOR!
What happening is site #1 and site #2 invoice the sales the same, so Paypal see's payment for ORDER12 but ORDER12 has already been paid for by the other site, so it rejects payment.
What I need to do is change in ordering system. Either add a static letter or bump the invoice numbers up to 10,000 on one of the sites..