Can't use same for loop var

[katat]

given:

fn main(pub public_input: Field, private_input: [Field; 3]) {
    let mut sum = 0;

    for ii in 0..3 {
        sum = sum + private_input[ii];
    
    }
    for ii in 0..3 {
        sum = sum + private_input[ii];
    }

    assert_eq(sum, public_input);
}

it throws error at the second for loop:

   ╭─[for_loop:7:1]
 7 │     }
 8 │     for ii in 0..3 {
   ·         ─┬
   ·          ╰── here
 9 │         sum = sum + private_input[ii];
   ╰────
  help: the variable `ii` is declared twice

The cause is the TypedFnEnv use var name as key to store vars, but it doesn't remove the vars that are out of scope.