evrybiont

git remote rm heroku - this will remove the heroku remote from your application

git remote add production <production apps heroku git repo url> - this will add a new remote named 'production' pointing at the production apps git repo url (you can get this from the My Apps page on heroku.com

git remote add staging <staging apps heroku git repo url>

git push staging master

git push staging local_branch:master
 

evrybiont

Multiple SSH Keys settings for different github account

create different public key

create different ssh key according the article Mac Set-Up Git

$ ssh-keygen -t rsa -C "your_email@youremail.com"