Yes, that is a 3rd generation model. I have a couple of them as well as an Apple TV 4K Gen 1. They work fine on the same network using the same Apple ID but remote control inputs can be an issue if you are going to use them together in the same room. What I noticed with mine is that the 3rd Gen remote control will control both of them right off the bat when placed near one another. The new Siri Remote Gen 2 uses Bluetooth 5.0 and only controls the Apple TV 4K Gen 1 in my setup. Of course, results will vary. If the 3rd Gen in your setup is a set it and forget it situation, you should be good streaming with the 4K model and Siri Remote control and not mess up the 3rd Gen. What is the model of iMac in use there?