Duplicates Created by Marketo form

We have a multi-part form that draws on a .json doc of values as a gateway question, and then goes to the second part of the form that asks for the user's info.

Somehow this form is able to create dupcliates (see image).

Perhaps the cookie is not functioning correctly? If it doesn't recognize me, it's blank, and when I fill out the form it makes a duplicate record.

Any experience with this?

Thanks for any help!