Why no Blu-ray/DVD combo discs?

[BigJay]

I'm an owner of one Blu-ray player and there are four other DVD players in my home.

The Blu-ray player (PS3) is for my "home theater" set-up.

The one thing I find discouraging is the lack of Blu-ray / DVD combos.

HD-DVD (the obvious loser) has not all, but several titles available in the HD-DVD / DVD format.

Is there any reason that Blu-ray is not doing this? (Contractual, etc.)

I'd love the ability to enjoy pure and crisp HD on my main set, but sometimes the kids want to watch a movie (Cars, Ratatouille) on the "play room" set and I don't want to have to purchase two copies of the movie.

Are Blu-ray / DVD combos coming out in the future?

If you ask me, it would be a positive step for Blu-ray - hey, sure, you'll get the HD experience on one side of the disc, and the other will be perfect for trips in the mini-van or watching at Grandma's house over the holidays...