Your idea is quite an edgy, contemporary one, but it is so easy to cock up completely !
If you wish to use two different wallpapers, stick to one per wall (count the Chimney breast wall and back walls as one).
Choose designs from the same tonal colour if you want two different patters, or the same pattern in two different colours.
Choose wall papers from the same wallpaper family. In the store where you decide to buy your papers, they will be put together in the same book for easy reference.
At the end of the day, we all have different tastes. Go with your own tastes.