You may have noticed that ARS ensures that the proxyAddresses attribute is updated to match the value entered on the general tab (email field). The email field value is not currently checked against the Exchange and can generate duplication of proxyAddresses attribute values.
This has been accepted as a product defect (TF00469697).
This will be fixed on a future release of the product. If you require this immediately corrected, please contact support for a hotfix referencing the defect ID TF00469697.