"A Dual Disc is a rather new type of disc. One side behaves as a Compact Disc (mostly containing audio), the other side contains mostly DVD-Video. The audio part of this disc is not always played well as the disc is 1,5mm thick (normally 1,2mm) and the audio layer on which the laser has to focus is situated at 0,9mm and not on the normal 1,2mm."
DualDisc is a type of double-sided optical disc product developed by a group of record companies including EMI Music, Universal Music Group, Sony/BMG Music Entertainment, Warner Music Group, and 5.1 Entertainment Group and now under the aegis of the Recording Industry Association of America (RIAA). It features an audio layer similar to a CD (but not following the Red Book CD Specifications) on one side and a standard DVD layer on the other. In this respect it is similar to, but distinct from, the DVD Plus invented in Europe by Dieter Dierks and covered by European patents.