You can easily add new devices right from the DUO authentication prompt at office 365
Details
1. Welcome Screen
When your previous device was set up, you may have chosen to automatically push or call your device. If so, DO NOT respond to the DUO prompt on the device and instead press the Cancel button (see image below). If this does not apply to you, continue on with the instructions.
To add a new device, click Add a new device.
2. Add a new device screen
Choose an authentication method and complete the second factor authentication to begin adding your new device.
If you’re adding a new device to replace one that you previously activated for DUO Push, don’t select the DUO Push authentication method on this page. If you have a new device with the same phone number then you can authenticate with a phone call or SMS passcode.
3. Device type selection
Proceed with the device enrollment process as shown in the initial registration guide. As an example, let’s add another phone.
4. Device details (assuming you selected Mobile Phone)
Enter and confirm the second phone’s number. Press the Continue button.
Select the new phone’s operating system. Press the Continue button.
5. Install and activate the DUO Mobile app (if you selected Mobile Phone)
Install DUO Mobile on the new phone following the instructions on the screen (Android example below) and press the “I have DUO Mobile installed” button when you have installed the app.
Scan the barcode with the DUO mobile app to activate the account.
6. Confirmation screen
The new phone is added and listed with your other enrolled devices.
7. Configure Device Options (optional)
Click the Device Options button next to any of your enrolled devices to view the actions available for that type of device. You can Reactivate DUO Mobile for an enrolled smartphone, Change Device Name for any type of phone, or delete any authentication device.
Change Device Name
Clicking Change Device Name will open up an interface to change the display name of your phone (hardware tokens can’t be renamed). Type in the new name and click Save.
After successfully modifying your phone’s name, not only will you see this from now on when managing devices, but it will also be how your phone is identified in the authentication dropdown.
If you want to continue using your original device with DUO, you can specify which of your devices you would like to be the default. Click the Default Device: drop-down menu and pick your default device for authentication. Click Save if you’re done making changes.
If this is the device you’ll use most often with DUO (and it has the DUO app installed) then you may want to enable automatic push requests by changing the When I log in: option and changing the setting from “Ask me to choose an authentication method” to “Automatically send this device a DUO Push” or “Automatically call this device” and click Save. With one of the automatic options enabled DUO automatically sends an authentication request via push notification to the DUO Mobile app on your smartphone or a phone call to your device (depending on your selection).
Remove a Device
If your new device is replacing the one you previously enrolled, you can remove the device you won’t be using any more for authentication. Click the Device Options button next to the device you want to remove, and then click the trash can button to delete that device.
You’ll have the chance to confirm that you want to delete that device.