You can, indeed, have both a fan and an artist account. First, you'll need to log out of your fan account. Then, head on over here to sign up as an artist. To avoid login headaches, we highly recommend you use a unique username, email address, and password combination.
Once that’s done, you can connect your shiny new artist account to your fan account so that they can be managed using the same login credentials. You’ll want to:
Log out of your artist account
Log in to your existing fan account
Connect the new artist account in Settings > Connected Accounts.
Since collections are populated by payment email, if you've made purchases with multiple email addresses in the past (or do so in the future), you'll be able to link any additional emails under the Fan tab on your Settings page.