nvm-windows creates a symlink in C:\Program Files\nodejs and when you run nvm use x.x.x it updates the symlink to point to the right version under C:\Users\%user%\AppData\Roaming\nvm\vx.x.x (this is where different node versions getting installed)

When you do run nvm use x.x.x, the active version of node is automatically updated across all open console windows. It also persists between system reboots, so you only need to use nvm when you want to make a change. source

So it is highly improbable you can run two different version in parallel.

Probably a bit late on answering this question, but I came across the issue and thought I'll update it with something I found!

For context, I needed to run different node versions across different terminals on windows, and found that nvm-windows does not support it because of the way it works as per Gabriel's answer on top.

Found this wonderful work on github - https://github.com/davfive/nvm-session and all credits to the creator, for building a simple workaround for this. The steps to get this working are clearly explained in the README of the repository, and helped me solve my problem!

However, I believe it requires you to use git-bash/any such bash-supported terminals on windows to get this working!

Thank you!