What exactly does
Each player may only have a maximum of one instance of each unique card, by title, in play.
on p22 of the Reference Rules, under Unique Cards, mean?
For example: if I use Yoren to put my opponent's Margery Tyrell into play, is that me having her in play (since I control her) or my opponent having her in play (since he owns her)?
In particular, if my opponent has Margery in play, does that stop me using Yoren to put another copy of her into play from my discard pile? Similarly, if my Yoren has put my opponent's Margery into play, does that stop my opponent putting another copy of Margery into play under his control?
Alex