Reorganizing an array without sort() and doubles

I have an array like this named contents:

contents[0]='<button id=' + randomChar0 +' class="btn" onclick="check('+ f + randomChar0 + f +');">' + randomChar0 + '</Button>';
contents[1]='<button id=' + randomChar1 +' class="btn" onclick="check('+ f + randomChar1 + f +');">' + randomChar1 + '</Button>';
contents[2]='<button id=' + randomChar2 +' class="btn" onclick="check('+ f + randomChar2 + f +');">' + randomChar2 + '</Button>';

I have tried to rearrange it with this code:

function shuffle(array) {
  var currentIndex = array.length, temporaryValue, randomIndex ;

  // While there remain elements to shuffle...
  while (0 !== currentIndex) {

    // Pick a remaining element...
    randomIndex = Math.floor(Math.random() * currentIndex);
    currentIndex -= 1;

    // And swap it with the current element.
    temporaryValue = array[currentIndex];
    array[currentIndex] = array[randomIndex];
    array[randomIndex] = temporaryValue;
  }

  return array;
};

calling it like this:

shuffle(contents);

from How to randomize (shuffle) a JavaScript array?

But this Method gives me doubles quite often.

Any idea how to make sure the buttons always change their order without any doubling and without using sort()?