Sometimes you need to keep two upstreams in sync with eachother. For example, you might need to both push to your testing environment and your GitHub repo at the same time. In order to do this simultaneously in one git command, here's a little trick to add multiple push URLs to a single remote.

Once you have a remote set up for one of your upstreams, run this command with the same remote name and the URL of the second remote:

git remote set-url --add --push [remote] [remote URL]

Note: The first time you run this, it might overwrite the default push URL so you'll have to re-run the same command again with the original URL remote URL.

Once set up, git remote -v should show two (push) URLs and one (fetch) URL. Now, pushing to this remote will push to both upstreams simultaneiously.