Since my original post I have talked to two other individuals that this has happened for, one got the Rabid Completionist achievement right after the intro mission on difficult, but before doing that he had completed normal difficulty 100%... Also another friend who had missed one or two of the secondary objectives on normal, upon completing those objectives on hard that he had previously missed, the achievements for both Normal 100% completion and Difficult 100% completion unlocked, I'd say its pretty safe to assume that this may have been intended by the developers, since it wasn’t a one time thing...But incase it isn’t I would strongly recommend everyone who is interested in this game to knock it out, it only takes about 4-7 hours at the most for 100% normal, and then all that’s left is to beat it on hard which I ran through in under 1.5 hours, of course there still is 15 snakes to kill/10 bee hives to destroy, but those are freebies practically...So everyone go out and get this actually really fun game and get a free 120 point achievement along the way, before there is an update...
100K in 9 months 8 day...WooHoo
JAIL is not FUN, ACHIEVEMENTS R!!!
...After nearly a YEAR Hiatus I'm BACK...HELL YEA!