Welcome to the Support Communities!
You will find the movie in the Videos app on your iPad.
I'm including a link below that will explain all about renting movies.
I've also included a link to the iTunes Store so that you can report that you rented it twice.
- Find the email receipt for your purchase.
- Click Report a Problem under the app that is having the issue.
- When prompted, enter the Apple ID and password you used to purchase the item, then click Report a Problem.
- Click Report a Problem next to the item you are having an issue with.
- From the Choose Problem dropdown menu, choose the appropriate issue.
- Follow the onscreen instructions and—if prompted—type a description of the problem into the text field.
- Click Submit to have your issue reviewed.
I hope this information helps ....
Have a great day!