i18next interleaving race condition

gistfile1.js

"use strict";

var i18n = require('i18next');

const LanguageStrings = {
  "en-GB": {
    translation: {
      "SAY_STUFF": "en-GB said"
    }
  },
  "de-DE": {
    translation: {
      "SAY_STUFF": "de-DE said"
    }
  }
}

function randSayer(lang) {
  i18n.init({
      lng: lang,
      resources: LanguageStrings,
      returnObjects: true,
  }, function(err){
    scheduleNext();
  });

  scheduleNext();

  function say() {
    var expect = lang;
    var actual = i18n.t('SAY_STUFF');
    var mismatch = actual.indexOf(expect) != 0;
    console.log(expect, actual, mismatch ? 'Mismatch!' : '' )
    scheduleNext();
  }

  function scheduleNext() {
    setTimeout(say, Math.ceil(Math.random() * 1000, + 10 ));
  }
}

randSayer('en-GB');
randSayer('de-DE');