Well as the problem was just to return only one winner, I just evicted duplicates, which doesn't allow the other problem where you would want to return an ordered list of "winners" (?)
If that was the case, I would obviously choose another method to keep my results ordered (maybe an OrderedDict like you did)

scores only store the first candidate for each total score when iterating candidates, which is ordered, and so the order is "preserved" as I evict all duplicates (look at the setdefault method usage)

Maybe I shouldn't have used a dictionnary for this and just stored a winner variable updated when seeing a candidate with a better score, this would have been easier to read I think.