The Unintended Consequences of Duplicates in Marketo

Marketo Employee
Marketo Employee

Many thanks to Jep Castelein who pulled much of this information together and tested it.

The best practice within Marketo is to work toward having no duplicate leads , but there are times this happens, especially since Marketo treats SalesForce and Microsoft Dynamics as the source of truth. Duplicates in those systems will result in duplicates in Marketo, and to be clear, a duplicate in Marketo is defined as a lead with the same email address.

I'll use the following as an example

Marketo IDFirst NameEmail

When considering the implications and the behavior of the system with regard to duplicates there are few key areas ..

Batch Campaigns

A batch campaign for which both leads above qualify will only go out to one lead. In this case, it will go out to the one with the LOWER Marketo ID, that is, the one that was created first in Marketo. When the email is sent and clicked on, the activities will be attributed to that lead as well.. and if the link in question leads to a page with munchkin code on it, any activity will also be attributed to this lead.

Trigger Campaigns

These are generally not a problem because they are a "Batch of 1" although they do not de-duplicate in the same way batch campaigns do.

Form Fills

If a lead that exists in Marketo more than once fills out a form, if a cookie exists on the machine they're using, the form filled will be attributed to whatever lead is associated with the cookie.. if NOT, it will be attributed to the lead that was updated most recently in marketo, and of course then the lead would be cookied.

Web tracking

The cookie ID stored within a browser can be linked to only one lead, but of course every browser can have its own cookie, and those can point to different duplicates. This happens when

  • A lead clicks a link in an email
  • A lead submits a form

List Uploads

Uploads will update the most recently updated duplicate

Lead Scoring

This is a big one. Lead scoring is triggered off of things like form fills, web visits, etc, so it follows the rules above. Obviously your risk here is that you can have a split lead score, with different actions attributed to different leads, leading to artificially low lead scores. Its not a huge problem though since much of the lead activity ends up being associated with the most recently updated lead.

Interesting Moments, Activity Types

Activities can end up also spread over multiple duplicates, as with lead scoring.


Another effect of the activity being spread out so you may see lower click and open rates than you might expect. As with the above, its most likely that it's the most recently updated duplicate that is being reported on

So... if your business case requires you to maintain duplicates, just keep this behavior in mind

Level 7

Thanks for the post, John Mattos​. Do you have any recommendations about how to handle those duplicate leads from SFDC?

For example, I was doing some digging today and what I think is happening to us is that when a lead record in SFDC is converted to a contact record in SFDC, it's also creating a second lead in Marketo. This means that we consistently have two Marketo lead records floating around. I know that there is the "SFDC Type" on the lead record there, and I'm wondering if there is a way to trigger that field to switch instead of creating a second lead record in Marketo.

Additional information: When a lead is converted to a contact in SFDC, the Lead Record becomes inaccessible and redirects you to the Contact record. That means that two records still exist, and I'm assuming those are the same two records that now exist in Marketo.

Any insight you have would be helpful.



Marketo Employee

Hi Rachel Egan​ Well two things (and I'd probably recommend posting this in the discussion area for the benefit of the whole community)

1. We have a service offering called "Easy Merge" in which we merge duplicates in Marketo and Salesforce [Merging Duplicates Part II : Easy Merge ] which I highly recommend.

2. When a lead converts through the normal lead conversion process, the effect in Marketo is that the "SFDC Type" changes from "Lead" to "Contact" and the SFDC ID will then be the Contact ID.. so you should NOT be getting additional duplicates in Marketo because of that.

Are you using he default conversion process or something custom?

The note is also normal, the lead that was converted remains in SFDC, but its not really a factor in marketo at that point.

Level 8 - Champion Alumni

John and Jep Castelein this is a great summary thanks alot!

Not applicable

Great stuff John! I have 99 problems and 98 of them are definitely due to duplicates. We have a 1:1 SFDC - Marketo setup in our system, which I've heard is not common. Salesforce is often the center of many problems because the system doesn't approach duplicates like Marketo does. Additionally, treating SFDC as the ultimate truth is dangerous for us because sales doesn't always see/know/care about the things we track in marketing.

A word to the wise: make sure to work side-by-side with your sales ops team if they deduping in SFDC otherwise you could end up with a whole big mess in Marketo.

Not applicable

Recently just tacked a business case where we needed to duplicate leads coming from a specific campaign. This was due to separating direct vs indirect business. Such is life with channel.

I successfully built out a duplicate lead webhook process and as we use partitions and workspaces, was able to properly move my duplicate lead out of my normal partitions into what I like to call my black box of leads not to market to.

Channel gets their leads and direct continues to receive updates on the original so be it previously engaged with us before participating in the channel campaign.

I've gone through similar testing as above and found my cookie successfully updated my correct lead and left alone the duplicate. Scoring at first glance appears to be unaffected as my forms are all local to the correct partitions and workspaces.

I'd like to hear your thoughts on this though. Anyone foresee some challenges i'm not picking up on?

Not applicable

Hi Katie,

Most of the companies we work with have the 1:1 sync, which for data quality is the best practice.

RingLead can make those 98 problems disappear if you care to chat,

Level 1

Wish I'd seen this summary a long time ago.  A "must read" for anyone with duplicates in their Marketo database!

Level 2

Another point to mention is Durable Unsubscribe. With known duplication into an unsubscribed initial record, this behavior will unsubscribe all of the duplicate records that share the same email address.

While this is (IMO) the correct behavior, it can cause problems with some business processes where a sales team use a temporary mailbox if the email address is a required field in CRM.