You can duplicate a WSL distro by running wsl --export <filename> in PowerShell to export your distro a tar file, and then you can run wsl --import <DistroName> <InstallLocation> <FileName> to import it back to any location on your machine, under any new name that you like. To run this distro again, you can run wsl -d <DistroName> or you can set it as your default with wsl -s <DistroName>.

You will need to be on Windows 10 version 1903 or higher to access this feature. Check out this blog post for more info.