Hi JONNEWCOX123,
Thanks for posting this question in Apple Support Communities about the Apple TV and using game controllers. To answer your question, yes, you can use more than one game controller at a time.
If you look at the article Connect a wireless game controller to your Apple device, you will find this information:
Use multiple game controllers with Apple TV
Apple TV 4K and Apple TV HD support up to four Bluetooth game controllers simultaneously. If you're using a Bluetooth audio accessory with Apple TV, only one game controller is supported.
Some apps let you use an iOS device as an additional controller, which doesn't require a Bluetooth connection. For help using an iOS device as a controller in an app, contact the app developer.
This should help you with using both controllers so your kids can have fun playing at the same time.
Have a great day!