I was wondering this too... It IS possible. I had Google Generator TFA enabled on a Motorola device. I got a new Pixel and wanted to ADD a new authentication device. I signed in to the web interface. I deactivated TFA on web. I reactivated TFA on web. When the barcode poped up, I scanned with BOTH devices. (The same code was being generated on both devices in sync. I did not delete the Motorola Google Authenticator and was concerned that I would have duplicates after scanning the barcode, but Google Authenticator recognized Teamviewer account and did not add another). I entered the code to Verify TFA. QED I hope that helps.
... View more