Ever since the launch of Google Duo, one of the top criticisms has been that you can only have a single device registered at a time. That means a person with both a phone and a tablet has to choose just one of those devices to receive calls. But a few months ago, we got the first clue that Duo would soon enable users to link a Google account, making it possible to contact people with their email address rather than needing a current phone number. This also raised the question of whether or not multi-device support might be coming. As of Duo v27, that question can be answered... Yes, multi-device support is happening.
Teardown
Disclaimer: Teardowns are based on evidence found inside of apks (Android's application package) and are necessarily speculative and usually based on incomplete information. It's possible that the guesses made here are totally and completely wrong. Even when predictions are correct, there is always a chance that plans could change or may be canceled entirely. Much like rumors, nothing is certain until it's officially announced and released.
The features discussed below are probably not live yet, or may only be live for a small percentage of users. Unless stated otherwise, don't expect to see these features if you install the apk.
Multi-device is confirmed
There's really very little else to say about this one. All of the evidence to confirm multi-device support is spelled out in one line with the phrase, "If <email> belongs to you, sign in to use Duo on multiple devices."
That's it. Once you sign into Duo with a Google account, you will be able to use the same Google account with Duo on other devices without deregistering the previous one. There will probably be a limit to the number of separate devices that can receive a call on your account, but it will likely offer enough breathing room for almost all users.
<string name="linked_gaia_account_found_details">If '%s' belongs to you, sign in to use Duo on multiple devices. Or skip if you prefer to use Duo only on this device. To add devices, sign into your Google Account at any time.</string>
<string name="linked_gaia_account_found_title">We found a Google Account associated with this number.</string>
<string name="linked_gaia_account_found_skip">Skip</string>
The rest of the text basically explains some of the operation – essentially that you can use more devices by signing in with your Google account. There's nothing indicating if multiple accounts can be used on a single device.
So far, no other notable changes have turned up in the app or the teardown, but we'll keep looking. If you spot anything, let us know!
Download
The APK is signed by Google and upgrades your existing app. The cryptographic signature guarantees that the file is safe to install and was not tampered with in any way. Rather than wait for Google to push this download to your devices, which can take days, download and install it just like any other APK.
Version: 27.0.184200521.DR27_RC10