Same Cookie Id, Different Email Address

@Mark: yes

Jep - I am assuming a new lead would be created if the same individual (with a different email address) comes in through a list import instead of a form completion?

Not sure, I also thought it was the way you described it, until I tested it late last year. I asked around, and several people said it had always been this way. 

Is that a relatively recient change because in my past life that has been availible.

Hi Eric, Marketo will never update the email address on form submission, unless you stuff the email address in a different field.  

Please ignore this if I have missed the point but

But the simple answer is NO a new lead should not be created.

To Jack's first comment comment 


From the first paragraph, if the lead is submitted with the tracking cookie information then the lead is "tagged" or creates a relationship in the Marketo database between the lead record with the email address and the cookie record. This is a 1:many relationship structure as a lead can have one or more cookies but a cookie can have only one lead. 

If at some point in time later, the lead returns and fills out a form with the same tracking cookie and edits the email address, then upon submit, the lead's email address will be updated.  From my understanding, Marketo should NOT create a new lead in this situtation.  It would only do so if the lead created via the APIs did NOT pass the _mkto_trk cookie in the first place.

Just my two cents,

Cheers,
Eric

@Jack: if your application is smart enough to use a Cookie ID as Lead Key for that small set of Leads but not for other Leads, then yes, you can do that. 

I can speak from experience that if a known lead comes back and completes a new form that a new lead record will be created and their cookie will be updated to point to that new lead, rather than the old one.

I'm curious, for the first time visitor visitor that is cookied, what action did they take to have the API create a new lead record for them if not filling out a form on your website / LP?

If by the cookie ID is the same, you mean the _mkto_trk cookie, they are indeed the same value for the first email address and after a form is submitted with a second email a, but they are associated with different lead records.  We use progressive profiling forms, so if someone changes the email address on a second form submit, the form doesn't capture the intiial information (e.g. first name, last name, company name).  We have a smart campaign that alerts us when a new lead is created without these elements and then we look for other leads with the same IP address, and will merge them if appropriate.

Jep, is this something we can do for a small set of leads we have flagged but not others?