In extended format (I ask because I think is important know perfeclty rules, also if I don’t play, now, at that format) is possible play both Sycamore and Juniper?
No you cannot play both of them in one deck
Two other questions:
- If in a deck I have 2 different Stadium, I can play one of them even if there is in play the other one, even if the other one is mine?
- If yes, I can play the second in the same turn of the first?
Yes, since you can play a stadium as long as they are different stadiums (not like parallel city, which is technically the same card). However, you can only play 1 stadium per turn.