This was quite a while ago, even for me. I remember a gymnast at the U. of Illinois "breaking" the world record (in a gym, not in a track meet) with a two footed takeoff. This must have been just before 7 feet was exceeded, and the gymnast exceeded 7 feet. It was the subject of an article in a national magazine of the time (probably "Life" because I remember the photo.) As I recall, the two footed takeoff was already illegal, so there was no question of this guy going for the real world record.
I may have a few details wrong -- it would have been about 50 years ago, so I may be rusty. Pat Palmer