The two verses Devarim 14:11 and 14:20 appear to say the same thing except that v 11 uses the word "tzipor" and v 20 uses the word "of". Aren't they the same thing? If yes, what is the second verse teaching us that was left out of the first verse?
Rashi (on the two verses) says that the first is a reference to the bird of the Metzorah which is sent away live. It can be subsequently eaten and doesn't become forbidden as something used in the temple service.
The second adds a violation of a positive commandment to the already existing negative commandment about eating non-Kosher birds (there is another verse that does the same for non-Kosher animals).
So yes, they are repetitive, but the first one uses the word Tzippor to refer to a specific kind of bird to permit something additional.