Heres my question..

1. If I have Port Royal as my world and my opponent has port royal as his world how would the +3 bonus work?

Is the bonus from each PR in affect for both players?

2. Can you play the same world and level on top of the same world of the same level?

1.) The cards text states that Port Royal Friends gain +3. So yes you would get +6 for double port royals (played by you and your opp. at the same time). Unless theres a card text fix that says otherwise.

2.) Yes you can play the same worlds back to back, just once per a turn you can play a world.

Just in case your wondering you will NOT gain a double bonus of support if YOU play 2 port royals back to back. Your top most world is the only effect you get.

Hope this helps.=)