Please can someone elucidate what none of my grammar books seem eager to
explain and that is WHY are they 'passed over'?
Ah, just re-read your email and I think I see what you are asking (and Isa
9:6 was irrelevant, which confused me). Ok, the answer is that the reason
depends on individual case, i.e. you have to consider all of them, one at
a time.
This work has been done already and the results are presented on pages
315-318 of Ginsburg's Introduction, i.e. for every case.
Generally it is a case of "dittography", i.e. the scribe writing the same
word twice or an extra word by mistake...