Billings Pro does not currently support multiple account identities.
However if you would like to invoice for different companies, Billings Pro allows you to create different invoice templates. The caveat to this is that the reporting and accounts and dollar figures would all go into one company.
You can create two invoice templates and choose which template to use with each customer. On one of the invoice templates, you would not pull the identity from the app and simply have it entered directly onto the template. The account information would remain the same however, as Billings Pro does not have separate identities for accounts either.