Double-sided disk

[citation needed] Optical discs can also be made in single-sided and double-sided formats, often as an alternative to two-disc packages.

[3][4] The practice mainly applies to DVDs, but some companies have experimented with pressing discs with differing formats on either side, to varying degrees of success: Universal's first HD-DVD and Blu-Ray releases were double-sided, backed with a DVD version of the movie.

[5] DualDisc and DVDplus are two variants of the double-sided DVD format where one side is a compact disc.

However, these formats failed due to physical design flaws that impeded their compatibility with many commercial CD players.

[citation needed] It is more convenient (and cheaper) for videos or music to be released on two single-sided discs.