No, it is not two plastic layers with foam sandwiched in between. It is called "foamed" because of the manufacturing process which makes it half the weight of solid PVC. It is the same material all the way through. It is also called expanded PVC. All you need is the 3MM thickness (1/8"). There are uses for 1/4", but for panels, that's overkill.
No one lives forever, the trick is creating something that will.