alternate github account?

Is there a way to prove an alter-ego github account (as an employee in addition to the private one)?
I see a way to _replace_ it only...

I think, it'd be cool to allow to have several accounts/orgs at the same service in general.
Just like web sites are handled already (one may add a next site to the list).

This looks like sorta duplicate of #2476 and sorta followup to #783

No files or tests are named. Start by reading related issues #2476 and #783, then clarify whether the intended behavior is retaining multiple GitHub accounts or organizations instead of replacing one; done means the accepted behavior and scope are unambiguous.

Written by the indexing model from the issue text.