Saw a spectacular two tandem crash in about 1978 or '79 at a Kangeroo Baggs event in CA.
Bunch of tandems were not paying as much attention as they should have, and two tandems plowed into each other.
Stoker on the one tandem Jumped up and clear off the tandem . . . spectacular; the other stoker and 2 captains went down. Result some bent wheels, and a ruined weekend by inattention, for a couple tandem teams.