Duvet With Different Thicknesses On Each Side

Just like some couples need a mattress with different levels of softness, why not make duvets with different thicknesses on each side. People often prefer different thicknesses, and feel hotter or colder when they are sleeping. Why should one person be too hot or cold to suit their partner? Maybe it could be a Duvet cover with two sides stitched in, that you put a half width Duvet into each to suit the person on that side.