This information from http://laservideodisc.tripod.com/discreviews/id6.html:

"Alien" was first released as a stereo, non-CX, 2-disc/3-sided CLV issue from the U.S. plant. Side 2 has a unique LaserVision side identifier logo with music from Pioneer's "What it is, How it works" demo LD. The only other disc to have this logo was the initial US pressing of "Grease" on Paramount Home Video. "Alien" was pressed on two sides because, at the time, neither the US or Japan was able to make a CLV Extended Play disc that was longer than 50 minutes per side.

Quickly re-pressed in Japan as a 2-disc release [1090-80] with the same jacket artwork with only the blue '20th Century-Fox Video' logo replacing the MVC logo, the re-pressing was upgraded to feature CX encoding on all sides. The standard LaserVision side identifiers are present and the side-breaks are the same as the initial US release. Not until the re-issue on CBS/Fox [1090-80] did Alien become available as a single-sided disc.

Manufactured by Discovision Associates and has the glue spray or "green slime" unplayable dead side common on late Discovision discs. This version is harder to find than the later single-disc [1090-80] CBS/Fox edition.