I agree with @florian's recommendation, but if you need dual boot it could be done easily.
You need some hard drive space for new partitions obviously (on the same hard drive or another one). Then you just install other distro/version as usual - with one caveat.
One thing to watch for is grub (the bootloader). If you just install other distro/version, it's grub will rewrite your original one. Most installers (Fedora's as well) allow you not to install bootloader, that's probably what you should do. Then to be able to boot into your second distro you should update grub's config withing your first distro (with grub2-mkconfig -o ...), it should add boot options for the second (third, fourth) installed distributions automatically.
Also you can manually add boot options you need to grub's boot menu, it's not hard but I won't go into details here, unless you ask me.
If you've let second distribution to install grub, then every grub update will rewrite bootloader and it's config. It's easy to repair from within your first distro or from install usb key. Still you're better off not letting secondary distros to rewrite bootloader from the very beginning.
