I use 2 gaskets but I put them below the valley pan to seal Where the oil can be a problem .
You want a sealer That is fuel resistant , Right Stuff is great but not cheap
Could they have used four (presuming OEM-style one-piece stamped-steel) gaskets to resolve some kind of clearance problem? As if the mating surfaces between the intake and head were not quite coming together properly?
I've replaced a few of those one-piece valley-pan (intake manifold) gaskets on 440-4 and 440-6 when I had to pull one or more of the heads. I've even reused some of the intake manifold gaskets. I'm talking about the one-piece stamped-steel type. On both stamped-steel head gaskets and intake manifold gaskets, after a good cleaning, wiping the surfaces down with acetone, the only "sealer" I've ever used is that copper spray stuff (I think Permatex has a product). The product seals the more minor imperfections, such as pitting or micro abrasions.
But when you start talking about "The Right Stuff" I'm thinking of their really great RTV Sealant product, and that isn't something I would normally use on well-matched well-mating intake to head surfaces.
@Chryco Psycho seems to know his stuff, so maybe I'm missing something obvious, here.