If you have the old Ratewatch app installed and are getting multiple notifications on the same presentation, it's happening because it can't handle the latest notification mechanism we are using to notify you when the presentation is opened, then again when it is closed. To stop the alerts, click on the little arrow at the bottom right corner of your screen where the alert is popping:
Then double click on the binoculars to open the Ratewatch application. Then go to the settings and disable the in app notifications for presentation alerts. You will still get the email alerts and alerts within RW on your phone, but this should stop the desktop alert trouble.