Hi,
Thank you for posting in Symantec community.
SEP 12.1 RU1 has the following fix.
A notification for "new risk detected" is triggered repeatedly, despite longer damper setting
Fix ID: 2497657, 2212158
Symptom: The damper setting on a notification for new risks is configured for a specific time value. The first risk triggers the notification correctly. Subsequent risks before the damper period time incorrectly trigger the notification.
Solution: The damper option on notifications was modified to prevent this issue.
Do you see three years old singler risk detection triggering repeateadly?
If possible could you please attach the screen-shot?