Prepaid Multiline Initial Setup

I went to a nearby AT&T corporate store and converted 4 postpaid numbers to prepaid numbers. Each were set up with auto pay at the store. In order to get the multiline discount, I was told to go online and add them. I did the first addition and the amount that's going to be deducted next month looks fine. The problem is, I was required to make another payment for the second line (paid twice in one day). Looks like when I grouped them together I was charged again. Is the initial payment on that line lost?  Seems like I should be able to transfer it or get the charge reversed.