I believe this is an artifact of combining multiple devices into a single "any" trigger (any change on any device will trigger if at least one matches your criteria, even if the specific event/device isn't one that currently does). Separating your triggers into separate triggers for each device will work differently, likely what you want.
You may also wish to consider other options. Battery reporting is notoriously unreliable, which is one reason I wrote this custom app: [RELEASE] Device Activity Check - Get notifications for "inactive" devices, though you can still use it for battery levels if you want.
