exhuast leak

Ok I know this is nothing new to slanters but I'll be changing out the manifold gasket again to clear up a BAD ex leak at #1 cyl.
I have a remflex gasket in there now but I must have torqued it down too much because it has "pulled" apart from the expansion of the ex manifold. I bought a fel-pro set today at lunch and to my surprise there are 2 manifold gaskets in the box!!
So, should I use both or just one and have a replacement for when the fel-pro starts leaking .. again.. Also, This time I will be shaving the head mating surface of the manifolds to make SURE that it is true
Does that little flapper thing in the ex manifold need to be there or can I cut it out or weld it open?