I think a more probable understanding of the "Daniel" reference in Ezekiel is that it is same Daniel from the book of Daniel.
Even if you assume that the prophecies in the book of Daniel were written retroactively 600 years later (given the accuracy of described events) it does not preclude an actual powerful person of that name being alive at same time as Ezekiel, and being the basis for later attribution.
Both Ezekiel and Daniel are written covering a similar set of years. Both refer to a person named Daniel widely famous for his "righteousness". It would seem improbable that they were talking about entirely different people.
Again, had a lot of fun reading that.