Ikea Tretakt "Plug with remote control, smart" did not unpair

Hello,
I’m just new in the topic and happy to find this forum. I’ve a question and would be happy if somebody could help me out.

I bought two set of the Ikea Tretakt “Plug with remote control, smart” (I’m not sure if I’m allowed to post links to this website)

The plug is paired with the remote condition as it was purchased as a set.

When pairing with the ConBee III, the first (original) pairing should be lost.
With one set this works, I can set the switch and plug as desired via the deconz/Phoscon app.

With the second set, part of the the first (original) pairing has not been deleted, the plug still responds to the “off” command. Even if the rest works in the way I want it via the deconz/Phoscon app.

I have tried a multiple reset, can I remove this pairing in another way.

I look forward to your answers,

Best Regards oek