Identifying user via Dynamic Chat in browser cookied to different user

Hi,

I have a Marketo landing page that needs to display some of the user's data when they click through from an email.

To achieve this, the landing page has a hidden form that is populating with 2 unique values from the user's Marketo record passed via a URL query string e.g. ?r=1978234&p=2349873. Upon successful submission of the form (which happens without the user's knowledge), the user's data displays on the landing page.

However, when the browser has been cookied to a different Marketo record, the data is not displaying, presumably due to a conflict between the cookied ID and the ids being passed by query string. Our developers have tried to make the page reset cookies upon load but to no avail.

While displaying no data at all is obviously a better outcome that displaying the wrong user's data, this is a problem when one user has multiple email addresses and therefore multiple Marketo records.

For example, they may be cookied as tom@gmail.com (id:100001) but we have sent the email to tom@hotmail.com (id:200002) and I want the data from their hotmail profile to display.

So I want to give users a simple way to reset the cookie settings somehow if they land on the page and cannot see their data (other than asking everyone to enter their email address). I thought I could do this via dynamic chat dialogue.