Pay twice for an iBook

I downloaded, was charged for, and read an iBook. Then deleted (remove from all devices) when I was finished. When I wanted to go back to read a section of the book and clicked on the "cloud", it was again downloaded. Several days later, I got was charged again for the same book. Why is this happening? Is there anyway to get a refund? What should I do next time to avoid double billing for the same book?