Going back to javascript after years of polymer and react and this little gem has got me stumped, I'm trying to make a little library that can be included in my customer's web pages.

"use strict";
const MyLib = mylib();
function mylib() {
  const res = {
    init:(data) => {
        const doSomthing = () => {
         console.log('somthing', data)
        }
        const btn = document.getElementById('my-btn');
        
        console.log('REMOVING EVENT LISTENER')
        btn.removeEventListener('click', doSomthing, false);

        console.log('ADDING EVENT LISTENER')
        btn.addEventListener('click', doSomthing, false);
    }
  };
  return res;
}

if then if I call MyLib.init({some: 'data'}) twice I expect just one event listener to be on my-btn but there is 2, I don't get it?