error[E0428]: the name `add_two` is defined multiple times
  --> $DIR/conflict-name.rs:10:1
   |
9  | #[wll::export(add_two)]
   | ----------------------- previous definition of the value `add_two` here
10 | fn add_two(a: isize, b: isize) -> Result<isize> {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `add_two` redefined here
   |
   = note: `add_two` must be defined only once in the value namespace of this module