The third account would be for currencies that checkout doesn't accept, i.e. Euro, etc..
It's the only way to have a link to PayPal and hide the link to Google Checkout.
I guess it would be so much simpler if there was only a way to choose which payment methods show for each currency or product.
Regardless, this is a solution - although a slightly more expensive one @ 15usd per month!
Thanks for your help though..