Can I add multiple devices to my two-step verification?

Yes! It is strongly encouraged that you add at least two devices (for example your mobile phone and a landline) to your Duo two-step verification.  That way if you cannot access one device you have a back-up for getting your code and logging in.  Within the Two-Step Verification settings box, click on the link that says 'Add a new device' (under the shield) to add your second device. You can add up to five devices.