I have a couple of newb questions.

First if my opponent has the Crown of Winter in play, and it is currently Winter. What happens if I put the Crown of Mereen into play? Is it both summer and winter? I know that the White Raven and Black Raven cards knock each other out of play but what happens with the crowns?

Second question. If I have Darkstar (either version) in play and then an opponent makes me discard Darkstar (from Princes of the Sun) from my hand can I attach the older version as a duplicate to Darkstar or is it actually discarded because I cannot play it?

Thanks ahead of time for any answers.