Haha I've done something similar once before.. except I only used 1 extra membership. If its your main then its not a big deal But that would suck if its a goldfarming account or something LOL. I wonder if you could sell an account with alot of membership on it like that?
For those wondering, there was a bug in the payment page or script that handled it that lagged. I applied 5 payments because they all showed up as not working. But when I logged on it said i recieved 5 messages and 130days of membership. lol
I laughed that even for half a year it still says "Renew NOW to avoid losing member status"
On the bright side, you wont get any more emails about loyatly reward points being missed out on.