I solved the problem after many attempts and now have 72 channels.
- Remove the HDHomeRun DUAL from the network (unplug power or network.)
- Shutdown Channels DVR Server.
- Start Channels DVR Server.
- Check Channels DVR Settings Sources. The HDHomeRun DUAL should be missing.
- Attach the HDHomeRun DUAL to the network (plug in power or network.)
- Go back to Channels DVR Settings Sources.
- Click Add Source to manually add by IP, or the gear and then select Scan Network.
- Follow the prompts to configure the source.
I figured out how to remove sources from this post. Would have been much easier with a trash can icon.