Does anyone know if these alternates have ever been digitized?
Probably not; I have never seen it with alternates in the last 30 years in the typesetting world except during the 2" film font display days. Serif Gothic had a short life; it never was that popular in the advertising world.
what does it say in those little tags? ITC Licensed?
Yes, it does... but ITC doesn't have this version... If you look at the "æ" in the normal version of the font, you can see that that shape is used for the alternate version of the "a"... so these shapes are somewhere... but where????