HKDF collision between different salts

Cargo.toml

[package]
name = "scratch"
version = "0.1.0"
edition = "2021"

[dependencies]
hex = "0.4.3"
hkdf = "0.11.0"
sha2 = "0.9.8"

main.rs

use hkdf::Hkdf;
use sha2::Sha256;

fn main() {
    let ikm = b"my ikm";
    let info = b"my info";
    let salts: &[&[u8]] = &[b"my salt", b"my salt\0"];

    for salt in salts {
        let h = Hkdf::<Sha256>::new(Some(&salt[..]), ikm);
        let mut okm = [0u8; 32];
        h.expand(info, &mut okm).unwrap();
        println!("OKM is {}", hex::encode(&okm[..]));
    }
}

output

OKM is 1d615d90d1171347e5567571e5c8196665ae2481ef603ded8da93e0824ef37f2
OKM is 1d615d90d1171347e5567571e5c8196665ae2481ef603ded8da93e0824ef37f2