Hello Catherine,
Welcome to Apple Support Communities.
It appears you are getting double tracking in audio when using the Apple TV app on your Apple TV, correct? We're here to help you take a look in to that!
First, let's unplug and power off the Apple TV. Reset back up and test. If you issue persist, demo the Apple TV on a different TV to verify if it's audio output on the Apple TV or the TV. Here is a couple articles on these steps:
Play audio in Dolby Atmos or surround sound on your Apple TV
Adjust video and audio settings on Apple TV
If the issue persists, please don't hesitate to post a reply on the thread!
Take Care!