When dealing with duplicate leads, Marketo should stay consistent on which lead record is considered the active/current lead

When dealing with duplicate leads, Marketo should stay consistent on which lead record is considered the active/current lead

If you have duplicate lead records in Marketo, it's important to know which record Marketo considers the "active" record.  Consider the following example:

Sending Batch Emails

If there are duplicates within your email list, only one email will go out. It will be the lowest Marketo ID (created first). This record is also used to populate tokens.  Example:



Marketo ID

First name












In this case, the email will be sent to the first record with Marketo ID 2749. It will say “Dear Elizabeth” if you use a token for first name. Also, the activity entries will be attached to that record (sent, delivered, opened, clicked). When the email click goes to a page with Munchkin code in it, any web visits will also be associated with this record.

[EDIT 1/30/2018]: apparently this is not the case.  As you can see below in the latest comments, Aaron Dear uncovered a serious issue/bug - especially if you have a lot duplicates in your instance (in some cases, these duplicates are intentional).  Basically, there is no defined logic to determine which lead record is used when evaluating duplicates as part of a batch email campaign.

List Uploads

When a lead is included in a list import and the lead already exists in Marketo, it will affect the most recently updated record in Marketo (updated last) - in this case, the record with the first name "Beth".  If you're intention was to ensure Beth's record had the most up-to-date information so that some of that info could be used in an email send, you're out of luck.  Marketo will use "Elizabeth's" record for that send.

We’ve been running into issues with duplicate leads that exist in the same lead partition – specifically when sending batch emails that include tokens for Sales Execs (BDE) First, Last, and Email.  To ensure this info is updated before an email goes out, the marketer will make sure the list import contains the most recent data.  The emails still went out with outdated content/data.  Uploading a list with updated data won’t matter (when there's a duplicate) since Marketo doesn’t use the most recently updated record in Marketo when sending out the email.

Obviously, the main objective should be to deal with duplicates appropriately and regularly.  But this often is easier said than done.

When duplicates exist, I would like to see Marketo treat the active record consistently - in this case, the same for when sending batch emails AND list uploads - so that we can be certain our emails contain accurate personalization data.

To see Marketo's full list of duplicate rules, head over to the discussion: If duplicate leads are an issue, be aware of how Marketo determines which lead is active

Not applicable

Anecdotally, I can confirm lead id's get re-used. Been chasing data consistency issues for a while but to be honest didn't ever really believe the answer was the id's are flagrantly re-used.

Level 10 - Community Moderator

Thanks, pretty sure I've seen it, too. Luckily in totally custom apps we've (accidentally!) protected against it by tombstoning deleted leads and not reusing their old info. Like you I couldn't believe it would be this lame!

Marketo Employee

Could you please point me to the support ticket?

Marketo Employee

Dan - Based on our investigation it doesn't appear like Lead IDs get reassigned by design. If at all you are seeing that behavior consistently, then it could be a bug occurring in certain flows (most likely a edge case). We would definitely want to gather steps to reproduce and address it -- a ticket with the specific flow and clear reproduction steps will be super helpful to make progress.

Level 10 - Community Moderator

So is this true or not?

If not, why is support supplying such inflammatory information?

Sorry for the misunderstanding, a lead ID can be reused if a lead is deleted and then purged from the instance. A purge occurs about 30 days after a lead has been deleted which is the window for support to be able to restore a deleted lead.

So most likely which ever lead had the value of 46460 was deleted and then purged which left a hole that was filled by the next lead to be created.

Level 3

I've no repro steps, but I do have 2 smartlists you could glean if you can access my instance:

  1. SmartList 1: Created after December 1-15, 2017, Marketo ID under 50000 (which shouldn't happen if IDs are never recycled - since it would have incremented beyond this number)
    • #SL6076547B2
  2. SmartList 2: Created between December 1-15, 2017, Marketo IDs over 100000 (has tons more people - expected behavior)
    • #SL6076575A1

If you've access to the instance, take a peek if you'd like.

Community Manager
Status changed to: Open Ideas
Level 2

Has there been any development on this major issue  @Dan_Stevens_ @Aaron_Dear?