How to copy from one <select> to another?

Question

I am using the two sided multi select found here http://www.stevefenton.co.uk/cmsfiles/assets/File/twosidedmultiselect.html and need to add the selected options in the right

Answer 1

    One
    Two            
    Four
    Five
    Six






Add
Add All
Remove
Remove All

jQuery:

$('.add').on('click', function() {
    var options = $('select.multiselect1 option:selected').sort().clone();
    $('select.multiselect2').append(options);
});
$('.addAll').on('click', function() {
    var options = $('select.multiselect1 option').sort().clone();
    $('select.multiselect2').append(options);
});
$('.remove').on('click', function() {
    $('select.multiselect2 option:selected').remove();
});
$('.removeAll').on('click', function() {
    $('select.multiselect2').empty();
});

Sample Workout