one gasket is required,blue is the intake,maroon or tan color is exhaust,usually thicker.
if its at all loose,or if the exhaust pipe flange isnt perfectly flat,it will burn gasket out almost immediately.when installed,the pipe and muffler cannot be touching anything,as it will cause exhaust to be misaligned.
some people have installed without,a light bead of high temperature silicone sealant will help seal.snowmobilers do this all the time and my dodge v8 has been like that for years.