If duplicate leads are an issue, be aware of how Marketo determines which lead is active

[Dan_Stevens_]

Many of us deal with duplicate leads on a regular basis.  Today, I just learned of something that's been causing issues for us, as we were always under the impression that Marketo considered the lead that was "updated last/most recent" as the active lead - and the lead that would be affected for things like list uploads, email sends, etc.  That's not the case.  This could have significant implications if you have a lot of duplicates in your instance. I just posted an idea that hopefully will get enough attention and change the way Marketo deals with duplicate leads:

NOTE: if you head over to the Idea page ( ), you'll note that a serious flaw has been identified - specifically around the way Marketo re-uses old LeadIDs (when the original lead is purged from Marketo) and allows new leads to take on these old IDs.  This could have serious implications, for example, for those of us that leverage the API in our environments.

[Dan_Stevens_]

Here's a situation where you can mitigate the amount of risk (if duplicates are an issue).  Let's say you have an event program with 25 registrants.  10 of those registrants exist as duplicates.  But the most recent lead records are included in this program.  When sending out a reminder email, for example, as long as you define your smart list properly (e.g., member of program; program status is registered; etc.), only those QUALIFIED leads will be sent the email.  This is a perfect example where Marketo will, in fact, use the most recent lead record when sending out a batch email since that's the record that qualified in the smart list to begin with.

Hope this helps!

[Grégoire_Miche2]

Hi Dan,

Thx for posting this and the idea. Learnt something.

-Greg