I'm sure you could rig up some sort of 5+ player game of Steam Park with two sets, but it'll take some jury rigging -- particularly with regard to the order tiles. You might also want to rule whether a player can have both copies of a given ride in their park. I wouldn't do it (I'd just go with two separate games), but I can't see why it can't be done.
No. 2 starters have enough to play 4 or less, not more.Uh, not every thread is a Dice Masters thread?