This may occur when there is already a Constituent record in CRM for that Account_Id and Name_Id, which the sync does not know about when trying to insert the Constituent. This is usually the result of a conversion or sync migration issue. A subsequent instance of this issue are not known to occur after the sync is running normally.
It is not possible to link up the current CRM record back to the Team Approach (TA) account, so the solution is to delete the Constituent record in CRM to allow the TA record to sync over. Be sure to check for any CRM exclusive data on the constituent before deleting it, as that would be lost.