This message occurs when a clear event is received from an underlying domain, but the notification in question is already cleared. One scenario where this may occur is when momentary notifications are generated from underlying domain with a expiration time. After that expiration time has passed, the notification gets cleared in underlying domain, the Aggregation SAM and Presentation SAM. But the underlying domain would generate a clear notification, which would in turn be processed by Aggregation/Presentation server and result in this message. The audit logs in this case from the Smarts OI and SAM servers can be examined to see whether this is happening.
Resolution
Smarts SAM is working as expected and designed, and there is no workaround for this product behavior.