Having licensed the required technology from Nintendo, Sharp released the Twin Famicom exclusively in Japan back in 1986. It is a lovely, stylish and rare console that combines the Famicom console and its Family Computer Disk System in one elegant case, while handily adding composite video to the standard RF option.
Oh, and you can always try to own one of said beauties by bidding on this Twin Famicom eBay auction. It's a boxed console complete with two controllers and four games (3 on cartridge, 1 on disk). Seller ships to the Americas, Europe, Asia and Australia.