It's not poetical at all, it's just places the emphasis slightly differently, but generally they're interchangeable. My mother tongue is Slovak and I never had to learn Czech, as the two languages are so similar that I can understand everything and I am just lacking the active communication skills. Nevertheless, I can safely say, that the emphasis works almost the same in both Slovak and Czech.
You stress the first syllable, which is ne, as it is part of the word. It's just pure coincidence that the word ne (no) and the negation morpheme ne- (not) are the same, but they are two different things; the latter is an inflection creating a new, separate word, whose meaning is the negation of its related antonym word. Basically it means it's a normal syllable within the word like any other.