Function already defined.
#2020 Compile-time error
Function already defined.
Additional Information
The function is "X".
or
External functions may not be redeclared: for function "X".
Recovery
Compilation continues but no compiled source code file will be saved.
Explanation
Each function's prototype can appear several times in a
program, with the elsewhere directive, but the function's body must
appear exactly once.
External functions may be defined only once, though.