Marketo form - how to gather information that doesn't sync into Marketo

I've got a request to create a co-branded landing page. However, only 1 of our brands is in Marketo, so if we create a field for the user to choose either brand, we would not want the non-Marketo brand to enter Marketo. Is there a way to create a form that basically serves as a static list where we can still receive a notification in Marketo when the form is filled out so that the team can manually assign leads based on which brand the user selects, but it doesn't create new leads in Marketo?