why is the only profile photo I've uploaded posted twice on my page? How do I change that?

Not 100% sure but if you add more photo's it may rectify itself as it using the one pix as your profile photo and cover photo. If that doesn't work contact Rover support [Edit: Rover’s contact options have changed. Visit the Rover Help Center at https://support.rover.com/ to find the phone number, help articles, or chat with the team] and they can assist you