WordPress custom menu is more manageable menu from other menu system.
Here are two menu system in custom menu. One can managed from widget and other is to set up to theme.
This is very easy to add more then one custom menu in wordpress theme.
Just add below code in functions.php
Then you see the tow menu form admin panel. where you can set it up.
After that add the below code in theme file where you want to display custom menu.
For Menu 1
For Menu 2