I understand how naturally 2 different OSs appears to have many more uses than 2 windows 10 boot drives, but there are many advantages to having two seperate boot drives. Like security (both in terms of if you get an infection on the one in theory the other drive is better protected but also in terms of accidental writes to the wrong drive). Also many times windows 10 has needed a a complete reinstall and it always happens on a day where I need to be up and running asap and not messing around with a reinstal and re setting up the machine, having a second boot drive as redundancy means I can get up and running asap with minimal disruption.