Bilingual VHS editions : How They Work and why They're Interesting

Some countries release their films on VHS in different versions. A dubbed version which has the film in the language of the country, a subtitled version with the original audio with hardcoded subtitles in a different language, or a bilingual version is which both the dubbed version and English versions are played simultaneously. 
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The bilingual editions are most common in Japan as an means of watching films on VHS. How these versions worked was that two audios would play at the same time; one audio stream would play on the mono channel and another audio stream would play on the other mono channel. The viewer could decide which version they wanted to watch by unhooking the left or right cable. Typically the left channel would be the Japanese dubbed version while on the right would be the original English version. If both cables are left in, both audio tracks will overlap.

To tell if the edition you have is the bilingual edition, There will be a yellow triangle on the top left corner of the box, yellow on the spine, and a message on the back saying it has two audio channels.

Japanese dubbed version (日本語吹き替え)

Japanese bilingual version (二か国語版)

Japanese subtitled version (日本語字幕)

​For reference, dubbed versions are marked with red with the letters 日本語吹き替え, subtitled versions are marked in green with the letters 日本語字幕, and bilingual versions are marked in yellow with the letters 二か国語版.

Why is this interesting ? It shows that the VHS format is capable of holding two audios on a single tape. The Laserdisc format was also capable of doing this as well. How it worked on LD was that there would be two separate audio tracks (one digital and the other in analog, or on older discs; two mono soundtracks) with the ability to switch between them. Unlike VHS, bilingual editions are more common on Laserdisc as it was easier to switch between the audio tracks on Laserdiscs unlike VHS. Like VHS, subtitled editions were released as well as dubbed versions (the dubbed versions are not as common as VHS.) The ability to hold more than one audio track and switch between them would be incorporated into the DVD format as well as the Blu-Ray format.