The account owner will always be the primary recipient of an invoice, but you also have the option to add additional recipients.
If you want your account invoices to be sent to two emails, you can do so by starting in your account dashboard.
Click on your name on the upper right corner, and then click Settings.
Scroll down to Business Details where you can add an additional recipient by setting a Billing email.
Scroll to the bottom of the page and click Save.