As it states in the nas Help documentation, a message is considered duplicate when message text, subsystem id and severity are equal to the previous message with the same suppression key. This will reduce the events received by the consoles. That said, in some cases customers may still notice they are getting duplicate emails for what 'appears' to be the same alarm message (except for the values collected due to a threshold that was breached).
Example alarms received via email:
The disk usage for <hostname>.Disk.Disk Read Rate on xx.x.xx.xx:443 is outside expected limits (5287.60 > 1000)
The disk usage for <hostname>.Disk.Disk Read Rate on xx.x.xx.xx:443 is outside expected limits (4234.60 > 1000)
Customers should check their Auto Operator profiles that have EMAIL as the action and also check the Message Suppression settings. For instance note that the nas 'Skip Numeric Characters' option not only skips numbers as it pertains to the alarm message count of characters, but it also ignores them as it pertains to alarm message suppression. So, for example you might want to choose that option if you are receiving emails with duplicate alarm messages due to the fact that the numeric values in the alarm message changed because the configured threshold was breached again.
keywords: dupe duplicate email message messages threshold breach breached numeric value values redundant