If you have enough ports to connect both, there should be no reason why you would have to disconnect one. However, I believe you would have a problem launching a game and deciding which one it would use and so probably you would need to unplug it. (Perhaps shortcut parameters can adjust this). If I launch DCS with the rift plugged in, it will automatically launch on the rift, you don't get a choice to use your monitor. So you wouldn't be able to choose which headset you want to view it on either I would expect.