A. It’s not required, and many kippas do not have them, but I know where you are getting that from since the yarmulkas I wear have that double-layer. Think of it as a spiritual form of atmospheric layers. There’s that which is immediately above us, and that which is way-out above us. The basic idea of a head-covering is a reminder that we’re not the end all, be all, there’s something above to be mindful of. The double-covering concept is (for those interested in it) to help us realize both the “near-above” and the “beyond-above” which may sound way-out, but is very well explained in Chabad Chassidic writings.