.png){kind=link}
The story
Xonox, based in Minnesota, started developing Atari cartridges during the height of the 2600's popularity. Xonox capitalized on the novelty and perceived value of "double-ender" cartridges. These could be inserted into the console on one of the two ends, each end offering a different game. Different double-ender configurations could package the same game with different counterparts. Xonox was not the first company to try this; Playaround did it earlier with their adult-themed titles. Xonox eventually abandoned this idea and began releasing single versions of some of the titles previously offered as double-enders as well as a few new titles.
From Wikipedia’s article on Xonox, shared under CC BY-SA 4.0.4