They say this because with photo analysis symbols can be made out on some of the sticks. The UFOlogists claim that these are 'alien hieroglyphics' and that there was never any debris switch. The camera man also claimed to have handled the original debris and that the original debris is what he took the pictures of. It was not switched. Marcel, in 1978, also claimed that the debris was not switched (although he later changed his story).
However, there is an alternative explanation for the symbols. Charles B Moore, only living Project Mogul engineer, says that the early balloons he prepared were held together with a wierd tape. He said this tape had lavender, stylized markings on them, somewhat resembling flowers and odd geometric shapes.
What is really in these photographs? Remains from a flying saucer or a radar target from a Mogul balloon, held together with the odd tape?


Looks to me like mere tape. After all how are aliens going to fly across the universe in a spaceship made out of aluminum foil and balsa wood? Can any intelligent person ACTUALLY claim that the material in these photos is ANYTHING other than a radar target?
Heres a link to a pro-ufo website that actually claims the USAF allowed the press to take photos of an extraterrestrial spacecraft!
http://www.abduct.com/news/n52.htm