UIM supports automatic suppression of alerts so you don't get repeatedly notified.
So if you have a disk alert set for 95% full and your're at 98%, you'll get an alert message every time the CDM test runs from the CDP probe but it'll be just one alert - count just increments.
If you want it to be prevented from reaching the point of being counted, you need to identify it with a preprocessing script and prevent it from being propagated from there (return nil from the script rather than the event). Unfortunately, a preprocessing script wouldn't have easy access to the list of active alerts.
It might help to understand more of what your problem is with the way it currently operates.
-Gairn