os/windows/ InstallingMultipleInstances
First install an instance the normal way.
Then grab the image from here – the file is called ubuntu-jammy-wsl-amd64-wsl.rootfs.tar.gz
Then
wsl --import <Distribution Name> <Installation Folder> <Ubuntu WSL2 Image Tarball path>
e.g.
wsl --import ubuntu2204c C:\Users\mrflibble\wsl\ubuntu2204c ubuntu-jammy-wsl-amd64-wsl.rootfs.tar.gz
This also works fine in cmd or cygwin, though with cygwin you need to ensure the paths are Windows paths (use cygpath -w /nix/path
)