When a new lead enters Marketo from a form fillout or List Import, Marketo automatically searches for a lead with the same email address. If that lead exists, the existing lead is updated instead of creating a duplicate.
However, Marketo does not automatically de-duplicate leads who are already in your database. This is especially a problem for new customers who often have many duplicate leads in their database.
Also, if you add a new lead directly into Salesforce (through the Salesforce import process or web-to-lead forms) Salesforce will create a duplicate lead that gets synced into Marketo. When this happens, you can use Marketo to find and fix those duplicates.
The primary consequence of duplicates is that one lead record could have the most relevant information about that lead while your sales rep is looking at the incomplete duplicate.
For example, say that you have a duplicate lead in your database and that lead fills out a form on your website. Marketo generally updates the lead record that was most recently updated.
In another case, say you run a campaign to email your lead database and two duplicates are included in your campaign run. Marketo automatically detects the duplicate email address and ensures that only one email is sent to that lead. That email send and subsequent activity will be attributed to the most recently updated lead.
When you merge leads, their entire history is combined, and you can control which fields are kept in the final lead. You won't lose any information or tracking.
Most customers have many duplicates when they start with Marketo. After initially de-duplicating your database, the work to keep your database de-duplicated is usually very small. You should work to stop the sources of duplicate leads and make Marketo your single point of entry for all new leads.
Go to the Lead Database section of the app. Then click on the Possible Duplicates list in the tree.
Click the grid header that says Email. You can sort by email address to see the duplicates next to each other.
Select two leads that have matching email addresses. You can do this by holding the "control" key down while clicking on the two different leads. (You can merge more than two at a time, but start with two.)
Tip: Sometimes clicking too fast will make the grid select incorrectly. Clicking a little slower usually helps.
When you have two rows selected or highlighted, click the Merge Leads button in the toolbar.
A dialog will appear showing you all the fields that differ between the two leads. You need to pick which values to keep in the merged lead. Not every field is displayed -- just the ones that you need determine appear.
By default, the values from the most recently updated lead will be selected (with a check and highlighed yellow). To pick a different value for the merged lead, click the checkbox next to that value.
If you want to enter your own values for the merged lead, click the Custom field for that row then type in your own value:
When you're done, click Merge. The winning values will be kept in the merged lead; the other values will be discarded.
Important: Clicking merge will instruct Salesforce to merge the records properly. All Salesforce and Marketo activities are merged into the remaining lead. Nothing is lost. Campaign History is also kept.
You will notice that the Possible Duplicates list has a Smart List tab. Click on the Smart List and you will see it's using the "Possible Duplicates" filter on the "Email Address" field.
You can change this filter to search other fields for duplicates. Click the little green plus in the definition.
Note: You should use only one Duplicate Fields filter in your Smart Lists. If you want to check multiple fields, always use the green plus button to add multiple fields; don't drag in a second filter.
When you change the Duplicate Fields filter, you should sort the Leads grid by the column you're checking to put the duplicates next to each other.
Marketo offers a service for mass-merging of duplicates. Please contact your Customer Success Manager to inquire about this service.
When you merge leads or contacts in Salesforce, Marketo will also merge the matching leads in your lead database. See this article to learn more about how that works: https://docs.marketo.com/display/public/DOCS/Find+and+Merge+Duplicate+People#FindandMergeDuplicatePe...