Hi hapa_dude,
As LJGMDAD mentioned … you would be able to feel any difference between the firmness level on each side but not the actual “split” itself. There is more about split firmness mattresses in post #2 here.
The tutorial post includes a link to a list of the members here that sell mattresses online (in the optional online step) and many of these sell latex mattresses that use different types and blends of latex in a wide range of budgets and designs. Post #3 here also includes the ones that sell component latex mattresses and off the top of my head I believe that most if not all of them also offer split layers.
Phoenix