Not sure if this helps, but trying for the best …
Maybe the OP is refering to the public/private key pair, as in
If he wants to execute ‘git push’ to a git remote on which he has no write
access, he may need to use a different id_rsa (or id_dsa) key to obtain
write access rights to that other “account” of his customer (or add his
own public key to the project of the customer)??
Maybe the OP can publish the result of
$ git remote -v
on the different projects to make this clear ?
Searching for 30 seconds on the Heroku help pages, leads me to this passage
Add your SSH key to GitHub.
On the GitHub site Click “Account Settings” > Click “SSH Public Keys” > Click “Add another public key”
Maybe this is the one-time Account set-up the OP is referring to ??
If that is the issue, there are 2 options:
- add his public key to the project of his customer (via the Heroku interface) <= prefered
- use the private key of the customer on his local dev machine (<= not prefered)
HTH (but not certain),