If I recall correctly terms like "hoplite" and "phalanx" were just generic terms used by the Greeks to refer to heavy infantry, regardless of equipment or origin. For example in the Anabasis Xenophon refers to the Egyptian heavy infantry armed with tower shields and pikes as hoplites. A hoplite gets his name from his "hopla" or his equipment thus making him an armed man. It has nothing to do with over-lapping shield since hoplites for the most part didn't fight that way, they fought via disorganized and frantic charges where the semi-organized formation would lose any cohesion and turn into a mad dash towards the enemy.