New MQTT sensor shows two graphs

I just installed a new temperature sensor in my attic. It is based on Tasmota running on an ESP8266 and reports temperatures and humidity via MQTT. The configuration looks like this:

- platform: mqtt
  name: "Attic Temperature"
  state_topic: "tele/attic01/SENSOR"
  unit_of_measurement: '°C'
  value_template: "{{ value_json.SI7021.Temperature }}"
  retain: true
- platform: mqtt
  name: "Attic Humidity"
  state_topic: "tele/motion01/SENSOR"
  unit_of_measurement: '%'
  value_template: "{{ value_json.SI7021.Humidity }}"
  retain: true

The reporting seems to be working as expected but when I click on the icon to see a history graph, I see two graphs:

The sensor shows up normally in the states developer section. Also, the humidity sensor shows normally (one graph) in the history display. Any ideas?

In reviewing the post I just made, I caught a cut&paste error where the humidity data was sourced from a different sensor (motion01). I corrected that and restarted home assistant and now I only see one temperature graph for the attic temperature sensor. I don’t know if the problem is fixed yet, but I can’t imagine how the change I made would affect the temperature the way it did.