Problem understanding HA integration

I have a NodeMCU with OMG 1.0.0 and a SRX882 receiver. I have HA discovery enabled.
When I press one of my buttons, I see a device trigger XXX–YYY-RF. (XXX and YYY are hexadecimal numbers) Press another butten, get a device trigger XXX–ZZZ-RF. So far, so good.

In HomeAssistant I try to use these buttons as follows:

alias: button pressed
description: ""
trigger:
  - platform: device
    domain: mqtt
    device_id: xxxxxxxxxxxxxxx
    type: button_short_press
    subtype: turn_on
    discovery_id: XXX-YYY-RF
    id: Button0
  - platform: device
    domain: mqtt
    device_id: xxxxxxxxxxxxxxx
    type: button_short_press
    subtype: turn_on
    discovery_id: XXX-ZZZ-RF
    id: ButtonA
condition: []
action:
  - service: telegram_bot.send_message
    data:
      message: "{{ trigger.id }} pressed"
mode: queued
max: 10

However, when I press either button, HA tells me that both triggers are fired.
Do I misunderstand the function of discovery_id?

Hello,

Maybe @odyno could jump in and help