mkt_tok and existing cookie - How will this work?

[Taylor_McCarty]

So I am curious how this might work. We have established a different unique identifier for our instance which allows for multiple records with the same email address. Historically in the past we were told to disable mkt_tok and even have some javascript set up towards making multiple records instead. I have been working on improving our instance and working towards utilizing mkt_tok more to help us. My question is this:

If I have a person who has 2 records, record A is getting updated with web activity from the existing cookie on the computer. Then we email this person from record B and include an mkt_tok, which record will then start tracking we activity? The record tied to the cookie or the record that had the mkt_tok email link clicked? 

[SanfordWhiteman · Accepted solution]

An existing associated cookie takes precedence.

[Taylor_McCarty]

@SanfordWhiteman I have a follow up question you might be able to answer. Given that my instance is using a different unique identifier and people can exist in the database with several different records. How would cookies relate to this? Would the first record created that got tied to the cookie be the one getting updated with all the web activity? Then what about if the person clears history and cookies? Guessing it would then tie the new cookie to whatever record matches up with another form fill, whether that be a new record or existing?

[SanfordWhiteman · Accepted solution]

When you use a compund primary key (Email + additional field) then an existing cookie association will not change on form fillout unless you also delete the cookie and create a new one.

[Tony_Mayse]

The two records will be merged. For more on the expected behavior: https://developers.marketo.com/javascript-api/lead-tracking/

[Taylor_McCarty]

The records won't be merged in our instance because their unique identifier is different. Our instance doesn't use email address as the unique identifier, we use a custom field.