The example given is actually one generated by the XCSoar program (hence the XCS in the middle of the file name). The program allows the user to chose any three characters for the "unique code" (AAA in this case).

So it is possible for there to be two files from different competitors with the same file name.

Having been a contest scorer for the last 4 years I know that this can occur and use the practice day or the first contest day to sort out those kind of conflicts.

Mike