Oh man was I looking for something like that. Duos has 24 players while solo only has 12, so duos is just better for xp. So this would fix that!
Would be great if it was only for extended modes. Why? Well because you spent twice as long to build, but you receive the same amount of xp in regular time build modes. Not to mention that a lot of players will leave the extended mode before it ends, so during voting there are like 8 people.