Hi @hybridblack, thanks for your query. Whilst this is an intriguing setup and something we may look at supporting in the near future, I am afraid that for the time being, the Tobii Core Interaction Software in conjunction with our consumer level eye trackers (EyeX, 4C) only supports one connected eye tracker at a time.
That being said, depending on which hardware you have, for example Tobii Pro Devices, you may have greater potential flexibility in your setup. If you could kindly let us know your current devices specification, that would be helpful.