It is possible to have multiple Authy apps running in parallel. You will receive notifications on all your devices when trying to log in, approval on one of them will authenticate your login.

After the installation of a second Authy app, you can approve the new app with a existing device. 

You will get a request in the app to approve the access.

Follow the instructions given on the screen.

Next time you log in to any Nord Pool system, you will be asked to approve the login from any of your authenticated devices.