Got another set, 1980 XXII Summer Olympics in Moscow, the ones that US boycotted.
The case of 50 lire I would call a design error. Signore Crocetti seems to go overboard trying to cover a broad spectrum of sports. Yes, at that time both Summer and Winter Olympics were held the same year, but the obverse explicitly states "XXII Olympics" which were Summer Olympics in Moscow. Since the Winter Olympics started later their numbering is lagging behind. In 1980 it was XIII WO in Lake Placid, USA. Interestingly, XXII WO are coming up in 2014, and they will be held in Russia as well, city of Sochi.