nice. when in doubt, clean 
Apparently going back and forth in VSCode via file-> open recents where I am developing code for both the argon and xenon...
maybe try out the new multiroot workspace support we've added in the alpha7 update: Developer Preview Changelog - January 14, 2019
you'll still need to clean regularly (e.g. when switching the project you are building) but at least you'll have all your projects open in one view 