It's a prologue that shows what happened to Carol Brady's first husband. The Real Roy and the imposter find the other horse statue and the imposter discovers that Roy has sent the first statue to his wife, Carol. Then during a storm, on a boat, the imposter cuts the engine wires and jumps overboard, leaving the real Roy stranded to die.
That might have worked - if not for the fact that, trivially speaking, Carol's former married name was Martin, not Hinkley (as in the Prof's real name on Gilligan's Island was Roy Hinkley) - get the drift?