There are two programs recording. It is not possible to tune to any thing else. I tried through web app and the NVIDIA SHIELD TV Android TV app (logs submitted).
192.168.0.159 (HDHomeRun EXTEND)
Tuner 0 Channel: 189.000 MHz
Tuner 1 Channel: 683.000 MHz
192.168.0.160 (HDHomeRun EXTEND)
Tuner 0 Channel: none
Tuner 1 Channel: none
192.168.0.161 (HDHomeRun EXTEND)
Tuner 0 Channel: none
Tuner 1 Channel: none
Edit: I have verified 160 and 161 are responding to web requests to watch TV (watched a bit via MPC-HC).
logs.zip