Only sort of.
An explicit double negative, like mi na na nelci, is a positive.
This means that, if a sentence like mi na nelci is followed by na go'i, you're still saying mi na nelci
But a negative answer to a negative question, thus:
xu mi na nelci
is still negative.
Similar to the confusion with na nei.
To give an always-positive answer, use ja'a. It's a simpler system than English, where you have to notice the form of the question when answering "yes" or "no".
na go'i is always negative.ja'a go'i is always positive.