Forms: Post to another Mautic form?

I have two Mautic instances (installed on the same VPS).

I have created an identical form on both instances (the same fields that are named the same thing). The from at has the form action to post the results to

When I fill out the form at the form submits successfully, however nothing happens at If I manually fill out the form at the form works fine.

What am I likely doing wrong?

I don’t have an authorization header, though I can’t imagine why I would need one…