Double sided key works with 2 different lock cylinders.

[zenish]

if like me you had to change the ignition switch or door lock and hate having to carry two keys you can have the profile of one key ground on one side of a key blank and the profile of the other key ground on the other side of the blank.then depending which way you turn the key it will open the door or turn the ignition.this will also work to use the same key for two different vans if the blank is the same.
i just had this done friday and love it.

 

[Josh P]

I like the idea of 1 key for 2 cars.

 

[BrooklynBay]

Thanks for providing this information to us. This is very good to know.