I have bought multiple core sets. Are we supposed to upgrade the Encounter Deck to 3x X cards?

I have been playing it that way and it seems to be a little bit easier in single player but gets harder with multiple people.

You're not supposed to do this, but you play the way you like ^^

ok kool thanks. is there an FAQ or something I can look at?

Nothing official yet but there's one thread in these forums that gather most of the rules questions (check for the FAQ keyword ^^).