Father Steve:

I would think we need a new word for such a new concept. There exists already the word doppelganger, which means literally the double goer in German. Why not coin two new wordsL

Einzelganger
and
Erstenganger.

The former would mean a living unit without a clone, and would mean literally a single goer.

The other word, erstenganger, would mean literally the first goer, and would specifically designate an original which had a clone.

Curly