we had our matrix cylinder head gasket replaced, but the replacement part purchased from Hyundai is thicker than the original part (ORIGINAL part is consist of two pcs gasket, the replacement is consist of 4 pcs gasket. what is the effect if we use the thicker part or should we discard the other gasket to just use two piece. please help.

I think you are confused with head gasket vs. valve cover gasket. Also, you are saying you replaced the gasket, then allude to still needing to replace it. Can you clarify your post? You might get a meaningful response that way.