Looks like my KS will finally be shipping soon and it seems i have an extra base set and advanced rulebook. Is there any reason to have two of these? I did have two copies of the original
Basically, if you want to have 8 players in the game or have people play multiples of the same species, the answer is yes there is value in it, more tiles and more minis means you can run missions with bigger crews and bigger ships. If you want to run a campaign, and your crew will up in rank, having access for both the heroes and the bad guys to bigger ships, really is fun.
But if you don't plan on ever doing that, then not as much.
Personally, I run at cons and for friends, so having more tiles, and tokens and minis helps a lot.