My understanding was that you needed a separate key for each Paypal. Least that's what I was told.
And it makes sense...Paypal would WANT to charge you as many times as possible..wouldn't they?
For more info on the hacking with screen shots...jump around this forum a bit. There's a lot of information..not just this thread.
http://www.ebaymotorssucks.com/phpBB3/viewtopic.php?f=9&t=660
Donna