Hashing using pbkdf2 returns different results despite the same salt

I tried to hash password 1000 times. Then hash the result again, but I get a different final result than password hashed 1001 times despite having the same salt

import {pbkdf2Sync} from "pbkdf2";

const hash = (password: string, iterations: number) => {
    const salt = "salt"
    let hashedNTimes = pbkdf2Sync(password, salt, iterations, 64, 'sha256')
    let hashedNTimesAndOnceAgain = pbkdf2Sync(hashedNTimes, salt, 1, 64, 'sha256')
    let hashedNPlus1Times = pbkdf2Sync(password, salt, iterations + 1, 64, 'sha256')

    console.log(hashedNTimes.toString('hex'))
    console.log(hashedNTimesAndOnceAgain.toString('hex'))
    console.log(hashedNPlus1Times.toString('hex'))
}