You can still use the second day. They don't have to be used consecutively. Regardless of whether or not you signed it, the first day has been used and the computer keeps track of that. If they don't have you sign it, you don't have to. They should make you sign it, because that's how they verify that it's the same person using it both days. But if they don't make you sign it, what can you do?
Thank you for the quick reply.