Seems fine to me. Personally, I'm a bit against having a really short normal version and a much longer hard version, but yeah. I think you can imagine some people taking advantage of this purely to give the impression that they mapped multiple difficulties. Anyway, I'll rank this one, probably it'll come back and haunt me in future when I tell someone "don't be a lazy bum and map a proper easy/normal map like you did for hard".
On second thoughts, why don't you have normal, hard and extended (the current hard), with hard being a shortened version of hard. Thoughts plz?