Steam Machine overwrites existing Steam Controller puck pairing slot

[vicnett]

Your system information

• Steam client version: 1782861641
• SteamOS version: 3.8.14
• Opted into Steam client beta?: No
• Opted into SteamOS beta?: No
• Have you checked for updates in Settings > System?: Yes

Please describe your issue in as much detail as possible:

Describe what you expected should happen and what did happen.

During initial set up of the Steam Machine with a Steam Controller that was purchased separately, when prompted to pair the Controller with the Machine's internal wireless adapter, the Machine overwrites the Controller's Puck pairing slot.

I would expect an empty slot to be used by default and/or to be prompted to choose a slot, so I don't need to re-pair the Controller with its original Puck.

Steps for reproducing this issue:

1. Go through the out-of-the-box Steam Machine setup using a Steam Controller that was not shipped with it (not already paired to the Machine)
2. Observe that the Controller's factory pairing to its Puck has been overwritten without user prompt or notification.