I had always heard that there was a famous counterexample to alphabetization, the [Zucker–Cox Theorem][1] (where they flipped the order for obvious reasons), but apparently the non-alphabetization in this case was apocryphal.

But indeed, non-alphabetization is very rare.


  [1]: https://doi.org/10.1007/BF01403189 "Cox, D.A., Zucker, S. Intersection numbers of sections of elliptic surfaces. Invent Math 53, 1–44 (1979)"