Leaving non stranded doesn't work either as it is a bound morpheme, a prefix not a word (in english) Usage definitely favors the latter. I'd use the two hyphens.
Except non is not an english word, it is a prefix of latin origin There's some uncertainty about whether. Which is why american style manuals will always ask you to merge it with the subsequent word, without a hyphen
For example, battlestar galactica used frack instead of fuck Another example is the use of snap instead of shit I think i may h. Atypical is by far the most common of the three, as confirmed in a google ngram search, so that would be my suggestion
Untypical is apparently most often used in the phrase not untypical Another google ngram search supports this I cannot find an entry for either in any popular online dictionary. It's an english adaptation of a latin saying
Meaning literally regarding taste, there is no dispute The phrase seems to be of medieval origin The origin is accepted as scholastic writings because of the grammar, which is atypical A more faithful latin rendering of the phrase might be
