When using a 433Mhz motion sensor, contact sensor or doorbell in Automations you get multiple On/Off notifcations each time it's triggered.
The problem has to do with the fact that the sensor sends multiple messages to make sure they are received by the Heart. And each time the Heart receives the message it triggers the automation that you have created. To overcome this problem you have to create a simple "low pass" filter. This filter will ignore changes that happens very frequent, thus only triggering once. See the attached image on how to configure the automation to only trigger once for the 433Mhz sensors.
- Press "Advanced"
- Check "Add duration" box and type "1s"
- Press "Done"