Also, aren't the sharpteeth from 11 screech and thud?
No they weren't. They were of the same species, but they weren't the same individuals. One of them was a reddish color, while neither Thud nor Screech were red.
And while one raptor from LBT 11 was the same color as Screech (blue), that doesn't mean it was the same dinosaur. There was also a raptor from the TV series that also looked like Screech, if memory serves me right, but she was a different dinosaur.
There have been cases in LBT where dinos look exactly the same but are different individuals. It is difficult to make unique character designs for many dinosaurs, so that's why the main characters look the most distinctive while less care is given to side and very minor, especially nameless, characters to make them unique. They basically look more like clones because using the same model saves time on animation.
An example would be the eggstealer herd from LBT 4. All of them looked like Ozzy (I didn't see any personally that looked like Strut). There was no evidence that any of them were Ozzy, and even if one of them was, there were many more and there was no way Ozzy was all of them.
Another example is in LBT 5, the opening sequence where two swimmers (corythosaurs in this case) were attacked. They both looked the same and it was, for me at least, impossible to tell them apart.
