When you run the IdFix DirSync Error Remediation Tool in your on-premises Active Directory Domain Services (AD DS) environment, "duplicate" is displayed in the ERROR
column for one or more objects.
This problem occurs if two or more objects have the same email address.
To resolve this problem, specify a unique email address for the object. To do this, follow these steps:
- In the UPDATE column for the object, type an email address that isn't already used.
- In the ACTION column, click EDIT, and then click Apply.
- Run IdFix again to look for more object errors.
Still need help? Go to the Office 365 Community
website or the Azure Active Directory Forums