The samples were taken at the same time so there was little doubt that they would have the same result.
It doesn't make a lot of sense though. From my understanding the yellow jersey, stage winner and a random rider are tested each day. That means that Floyd gave samples during stages 11 and 12 since he held the yellow jersey. Did they think that they could get away with doping that morning when his intent was to win the stage that day?
I read this post last week and thought it was interesting.
http://sports.groups.yahoo.com/group/brown-cycling-club/message/4703