I found a very DIY solution which will work for folks who are web developers.
I deleted the duplicate control unit by deleting a sensor on adtcanopyportal.com while my browser’s inspector window was open. I then replaced the device ID in the sensor deletion request URL with the device ID of my duplicate control unit. I was very careful to use the correct device ID which I found by inspecting the JSON response of the Test Mode final step — one of the control units had a status of WAITING_RECEIVE (bad) instead of WAITING_VERIFICATION (good).
I was then able to complete Test Mode with all of my sensors.
I noticed my panel firmware version is now N.1.0 build 3908. ADT Monitoring Service says “Not Active”. The radio status screen shows a connected status.
I called ADT to verify connection and they told me they are receiving alarm signals. I asked not to be transferred to the Canopy department but for the frontline rep to verify instead. ADT has been referring me to the Canopy department at 855-622-8941 when I call about technical things. When I called this number, it did not work nor does the “internal extension” ADT uses. I asked the front-line rep to stay on the phone while they transfer me. This evening I was told this number works Mon-Fri 8am-9pm ET and weekends 8am-7pm ET and they are closed for the evening.
They told me there is an ongoing Canopy problem and my address shows limited connectivity in the system. Perhaps I will test again with Wi-Fi offline next week to determine if the cell backup is still working.
Good luck folks!