Google's rules for having more than one account are being discussed here: http://forums.digitalpoint.com/showthread.php?t=758928 If you are an Agency, then you can have the same card and address details for as many accounts as you like. But you can't just create another account for the same business (unless you delete the old one first).
You can register as many as you want with the same name and card. Just make sure you link them using the My Client Center feature.