Contacts being duplicated after CSV file upload

[Minna_Pacanowsk]

We have noticed that contacts are duplicated in Marketo and SF when we upload a CSV list of contacts to invite to an event.

Some of the contacts will already be in our database (both in SF and Marketo), however, Marketo will sometimes duplicate the contacts which then leads to a duplicate also being created in SF.

Is there a way to prevent this from happening going forward, so that existing contacts are not duplicated?

[SanfordWhiteman]

To be clear: do you mean multiple Marketo persons with the same email address? It's important to know exactly what you mean by "duplicate."

[Minna_Pacanowsk]

Same person, with the same email address

[Grant_Booth]

Are you uploading them in Marketo or SFDC?
Can you find any pattern to when a duplicate is created? For example - maybe it's not created when the first name is the same but is created if it's different? I would also double-check that this isn't due to a permissions issue in SFDC. If Marketo doesn't have access to an existing record in SFDC, it won't sync down and it will create a new one.

[Minna_Pacanowsk]

Thanks for the suggestions – yes, have checked the file, no spaces/extra characters..

[Minna_Pacanowsk]

Uploading them in Marketo via a CSV file. Thanks for your response.

How can I check the permissions settings. I think that might be it!

[Grant_Booth]

Find an example where a duplicate was created, and then log into SFDC with the mkto sync user's credentials and try to look at the records. To go directly to the record you can copy and paste the SFDC ID from the lead detail in Marketo directly into the URL in SFDC.

[SanfordWhiteman]

Are you positive that the email address does not have leading or trailing spaces in the CSV for the affected people?