Meguiar's waxes can be layered, but two things must be tended to when layering waxes. 1) You must use the right waxes ("Layerable" waxes), and 2) You must recognize that at some point, "The Law of Diminishing Returns" takes effect.

Layerable waxes

A Layerable wax, is a wax that the protective ingredients used in the formula (natural and synthetic), are such that the protective layer left behind will not only adhere to the paint, but in subsequent applications, will adhere to itself. It also means that the carrying agents, be they solvent, water or something else, cannot be strong enough or in high enough concentrations to re-liquefy the previously applied layer, thus removing it during your attempt to add another layer.

Layerable waxes are primarily pure waxes, or protectants (as synthetic formulas are referred to) that do not contain chemical cleaners, or solvents that will remove the previous layer.

There is an exception to this rule and that is that it is possible to first apply a cleaner wax, and then apply a pure wax or pure synthetic over it.

The Law of Diminishing Returns
(Thomas Malthus "Essay on the Principle of Population" published in 1798.)

While this theory is generally used to discuss topics as they relate to the areas of economics and politics, it is a model that can also be used to explain in this case, the complex action occurring at the microscopic level on the surface of your car's finish.

The law of diminishing returns as it relates to layering,

A surface, such as an automotive paint, can only hold so much product before all you're doing is removing all subsequent coatings applied to the surface.

That is to say, after the first, second and in some cases a third application/coating, any more product applied to the surface is merely removed when you wipe the excess off after waiting for the product to cure.

At this point you've reached a plateau (or limit), as to how much wax (natural or synthetic) a surface can hold. Once you reach this plateau, all further applications of wax simply become excess that will be removed (and thus wasted), during wipe-off because it has nowhere to attach and layer.

Of course, this all depends upon your definition of the word "Layer".

If your definition of the word layer follows that of Webster's Dictionary:

2 a: One thickness, course, or fold, laid or lying over or under another

Then yes, you can layer to a certain point. For example, you can add multiple layers of layerable waxes until the limit to how much a given surface of an automotive paint can hold before each additional application is simply removed, or replaces a previously applied layer.

You cannot layer to the point of developing a measurable film-build without negatively affecting, or diminishing to some degree, the shine, optical clarity, gloss, reflectivity, depth of color etc. This is especially true if the product you're applying is not clear (in and of itself) to start with.

If your definition of the word "layer" follows that of definition used by some on the Internet,

Layer 1: To continually build a greater level of protection with each additional application, or layer, of a wax or protectant. (Natural or synthetic)

Layer 2: To continually increase shine, optical clarity, gloss, reflectivity, depth of color without end and/or after a plateau, or point of maximum potential has been achieved.

Then no, you cannot layer a wax, synthetic, natural, or otherwise.