Platform mqtt does not generate unique IDs

[davidlang42]

On every boot of HA, I get a bunch of errors from mqtt:

Logger: homeassistant.components.binary_sensor
Source: helpers/entity_platform.py:497
Integration: Binary sensor (documentation, issues)
First occurred: May 4, 2021, 1:43:39 AM (15 occurrences)
Last logged: May 4, 2021, 1:43:39 AM

Platform mqtt does not generate unique IDs. ID 7784XXXX already exists - ignoring binary_sensor.DEVICE_NAME
...

This is using yaml configuration as per /hasensors endpoint. If you can help me figure out what the actual issue with the config is, then I'm more than happy to fix the endpoint code to generate it!