Combining the cash in two prepaid Visa cards for one purchase?

Long story short I wanted to buy an item for an online game worth $9.99, so I cashed out $10 as a prepaid Visa. The problem is it gave me two separate $5 cards, so I was unable to purchase the item. I haven't been able to find a way to combine them without having a bank account (which I do not have). Is there anything I can do?