Really?
Where did you get that bit of information from? I am intregued as to how you can say that with such confidence. The reason I ask is that I am as certain as I can be that it is one person and that he has only been replaced on a couple of occasions since he took over from Perry McCarthy. One of the times was when they had the F1 car. If it isn't the same person, then the person concerned has a lot of explaining to do about his whereabouts on Top Gear filming days and why he has changed test days with his race team to fit around filming!
Now, I accept it could all be a big scam to throw us off the scent of what is really happening so any evidence you may have would be welcomed