EVGA’s InterView 1700, is a dual display system, features with two rotatable 17" TFT LCD displays in single unit. Each super-thin 17" TFT LCD display provides a 1440 x 900 resolution and they can both pivoted in almost any orientation.

The InterView screens rotate 180 degrees on a horizontal axis, inverting the onscreen image to be right-side up to viewers on either side of the desk. The screens also fold 90 degrees from completely closed to full width apart, accommodating any workspace while providing the convenience and increased productivity that working with multiple screens offers. Dual keyboard and mouse control make it easy for viewers to take turns manipulating data and images while the other viewer sees it from their side.

And you can see the gScreen spacebook 2009 also with a dual screen design. From http://www.gscreencorp.com/.