As far as I can tell, EINE was the first Emacs clone. It was written by Daniel Weinreb for the MIT CADR Lisp machine.
I have located EINE source code on PDP-10 backup tapes at MIT. I will submit a request for their release, but it will probably take a long time before they appear.
Side note. The second clone would be SINE (as hinted by the name), and then Multics Emacs. It's already part of this collection and can also be found here: https://github.com/ArchMach/Sine
As far as I can tell, EINE was the first Emacs clone. It was written by Daniel Weinreb for the MIT CADR Lisp machine.
I have located EINE source code on PDP-10 backup tapes at MIT. I will submit a request for their release, but it will probably take a long time before they appear.