Dynamics Sync Error - "A record was not created or updated because a duplicate of the current record already exists"

Issue Description
When syncing records between Marketo and Dynamics, an error is received of "Marketo is unable to update the following records in Microsoft Dynamics" due to "A record was not created or updated because a duplicate of the current record already exists".

Issue Resolution
The reason for that error is due to custom de-duplication rules set up in Dynamics, specifically when Marketo inserts a lead record or updates lead and contact records. There are a couple ways this issue can be addressed:

1) Your team can review the custom de-dupe rules in Dynamics and open them up so Marketo can insert/update records. We recommend this step first!

2) There is a Support tool that will allow suppression of the de-duplication rules set up in Dynamics for the sync user. With this tool, the sync user will be able to insert leads for the first time or updating a lead or contact. This process isn't typically recommended as a first step because it can lead to duplicate records being created, but if you'd like the suppression enabled, please reach out to Marketo support with the details of your request.

Who This Solution Applies To
Dynamics Users