If you register more than one Array Lock under a single PLACE in the Array app, you will be prompted to select a "PREFERRED LOCK". The lock you select to be the "PREFERRED LOCK" will be the one that you receive Geofencing notifications for. This applies to each place that you register more than one lock under.
For Example: If you have an Array Lock on the front door of your home and you decide to add one to your back door as well and you register it under the same place in the Array app you will be prompted to choose which lock you want to receive Geofencing notifications for, this will be your "PREFERRED LOCK"