For future reference, you probably should have used the --expand flag to add the www domain instead.
Originally, you created a certificate with guardianmc. net as the primary (and only) domain. You’ve now created a second certificate with www. guardianmc. net as the primary domain and guardianmc. net as a secondary domain. When you renew, you’ll renew both the original and new certificates.
The “expand” flag would have added www. guardianmc. net to your original certificate as a secondary domain. But since you now have your new cert, I’d probably remove (not revoke) your original - chances are you won’t be using both! 