If they did indeed switch the two vessels there must of been a great number of Harland and Wolff workers in the area that would of known of such a major change. I'm not saying they would have known about the "wanting to sink the ship" part but I know they would have told atleast someone about this switching of the ships and it would have been passed down especially after the sinking of the Titanic. I believe this theory was born just because of the fact that Olympic and Titanic were so closely alike in the first place. People are constantly making up and twisting stories, rumors and facts to make myths in which we all ponder what the truth really is...