コレも兼用しようと思ったらダメだった。１リポジトリにつき１keyだそうで。
https://help.github.com/articles/error-key-already-in-useOnce a key has been attached to one repo as a deploy key, it cannot be used on another repo. If you're running into this error while setting up deploy keys, check out this guide for more details.
