Adding Button for more light via MQTT

I am not relay new to HA, I had an installation in my old home. But paused now for 3 years an did a new installation in my new home. Base was a Debian 10, the installation installed docker .
I added an MQTT device wicht worked fine and I could add a Button for it. I added next device and aade a new button but both buttons work on the first device. I do not found who to do a conncetion between buttons and device.

Thanks for Help