How do I open multiple instances of Visual Studio Code?

Use

code -n

when launching the program. This "Opens a new session of Visual Studio Code instead of restoring the previous session." (from here).

The way I used this was by modifying my "Code" shortcut to include the -n parameter:

If it does not work, restart VSCode

Ctrl + Shift + N will open a new window, while Ctrl+K then releases the keys, and pressing O would open the current tab in a new window. You can then use menu File → Open Folder to have two instances of Visual Studio Code with different folders in each window.

⌘ + Shift + N and ⌘ + K for Mac.

List of helpful keyboard shortcuts can be found here.