My defective battery was literally going to explode. It was bluging out of the center and the metal cover was peeling off the back. My computer would conk out after it hits 50% cpu load. Anyway, I got my replacement battery within 1 business day so I was really happy. But then, the next day, I got another package from Apple and its another brand new battery! I was thinking "Oh, they must've sent me two different packages..." but when I read the shipping label, everything is printed exactly the same...down to the ACI ref, delivery, customer, package ID, etc #s. So I was wondering if I would get charged for two batteries if I only returned one.