Your OkiOki account is linked to your VAT number. Two VAT numbers therefore means two OkiOki accounts. In this way, you always keep both administrations neatly separated.
This also means that you can link a separate mailbox for both accounts, which OkiOki will then monitor.
Why are these separate mailboxes important?
Mailboxes in which e-mails from multiple administrations are grouped together, cannot be split by OkiOki. It cannot determine with certainty which invoices belong to which administration, as not every invoice or statement contains your administration's VAT number.
If you cannot or do not want to work with separate mailboxes, you can always opt to monitor your own mailbox. Then you will manually forward every incoming invoice email to your personal OkiOki email address, linked to the relevant administration.