Adding a Battle.net Authenticator to Multiple Accounts

The Battle.net Mobile Authenticator app can be attached to up to three different Battle.net accounts.

After you added the Authenticator to the first account: 

1. Log in to the Account Settings of your second account
2. Go to Security > Set up Authenticator (or Account Overview > Add Authenticator)
3. Skip the download because you already have the app on your phone
4. Select "Other Options: Set up a mobile authenticator"
5. Enter the security code sent to your Battle.net email
6. Enter the serial number found on your Battle.net Authenticator App

You can use the same steps to add the same Authenticator serial number to a third account.