Based on the first link, it seems as though zero and upper-case "O" are very similar. (My eyes cannot discern a difference, but I admit that my eyes are not top-notch.)
Old Timey Code fixes both of these-- it has a slashed zero and redraws the number 1 to be distinct (angles the top serif).
and having said that, forget authenticity, I really appreciate typefaces that make an effort to distinguish all characters.