I got the proof from these Web sites.
F-16
This Web site contacted the Thunderbird office and S. Sgt. Katherine Garcia said that the pictures are real but they took the shot from the ground. It appears that the two planes are almost colliding but they are really 500 feet apart. She says the bottom plane was going straight down and the top plane was gaining altitude and thats how they look close together. She also says that this hoax has been surculating the internet for quite a while but there was absolutly no danger to the Thunderbirds performance.
This Web site doesn't have any proof that it is a hoax but they say it is
Big Hoax