Highly possible.

Edited.

Surely, yes. But how frequently? They'll need to change shoes, too.

That's the easier part, I guess. Just keep two rackets!

Strange one this. The question is: What is it that makes a player good on a surface?

For Nadal on clay, it's HIS shot that he likes. He has an advantage because of his speed. The way the ball sits up gives him time to reach the ball and with his speed and consistency of shot you can't hit through him.

For Federer on grass, and indeed with any player on grass surely it's the way he can force the other player to hit the shot that is the advantage. Surely even a grass specialist doesn't like the way the ball skids through on grass, they just know they can be agressive and stop the other player from playing their shots.

So when Fed is on grass side and Nadal on clay, Nadal has major advantage because he has time to play his shots and Fed doesn't and when other way round Fed has big advantage because Nadal doesn't like playing his shots when he's on the grass side.

Think I've really hashed the explanation but hopefully you get my point. If this is genuine, it's pretty badly thought through. Just because one half is grass and the other is clay doesn't mean they all of a sudden have a level playing field. Also, they are going to have to adjust to a different play style every 2 games so surely it's going to come down to who adjusts the better rather than who is the better overall all court player.

all seems very odd to me