Multi-Time World/Olympic Gymnastics Champions on Same Event

Medals aren't everything, especially in a sport so rife with international political considerations, but they do count for a lot. And so does history. To win more than one World Championships and/or Summer Olympic Games individual title on the same event puts one in a very elite group and it shows that winning that title surely wasn't a mistake. Some quizzes are about demonstrating what you know and/or getting points. Some quizzes are more educational. File this one under the latter. I probably would not get more than 607 of these right. Indeed, I did learn a surprising thing or two, just making this quiz myself. This is a "Yellow Box" quiz, so just typing in a well-known name is not enough. You also need to know what they were known for doing. Please guess by the gymnast's LAST name. In the case of Asian names, either the first or last name will suffice. I have tried to make allowances for difficult spellings. Also, the 'Alternate' Olympics for both 1980 (USGF International Invitational in Hartford, Connecticut) and 1984 (Friendship Games in Olomouc, Czechoslovakia) were included in the data that made these questions.