But this new production, which opens on Monday, suggests another level of complexity. There are two Tristans, not one: Spyres dying as he stumbles through a tunnel that appears to float from the rear of the stage to the front, and his double, lying on an operating table at the front of the stage, with a doctor tending to him. At times, they trade places as their parallel worlds — “fable and table,” as the director calls them, one metaphysical and the other mundane and ritualistic — merge and reinforce each other.