error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
  --> $DIR/E0719.rs:1:33
   |
LL | trait Foo: Iterator<Item = i32, Item = i32> {}
   |                     ----------  ^^^^^^^^^^ re-bound here
   |                     |
   |                     `Item` bound here first

error[E0719]: the value of the associated type `Item` (from trait `Iterator`) is already specified
  --> $DIR/E0719.rs:6:42
   |
LL | fn test() -> Box<dyn Iterator<Item = (), Item = Unit>> {
   |                               ---------  ^^^^^^^^^^^ re-bound here
   |                               |
   |                               `Item` bound here first

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0719`.