Atmel-ice How to tell platformIO to use a specific device?


I have 2 atmel-ice programmers and I’m working on 2 lots of hardware each with a programmer fitted.
At the moment platformIO will only load using one of the plugged-in atmel-ice and I have to remove one of them to use the other?
How do I program platfromio.ini to use a specific unit?

Unit 1 ID
Info : CMSIS-DAP: Serial# = J41800055452

Unit 2 ID
Info : CMSIS-DAP: Serial# = J41800100324

Having the 2 units connected with different atmel-ice devices allows me to debug each unit in real-time rather than one at a time.

Kind regards,