Dynamic Drop Down List Validation

Question

How can I validate cloned drop downs wherein a drop down will be selected, the option will be disabled to other drop down lists?

Html Code

<form id="surveyForm" method="post" class="form-horizontal">
    <div class="form-group" id="surveyTemplate">
        <label class="col-xs-3 control-label">Options</label>
        <div class="col-xs-5">
            <select class="form-control user" name="employee[]">
                <option></option>
                <option value="1">Martin Luther</option>
                <option value="2">Mark Glovo</option>
                <option value="3">Michael Sei</option>
            </select>
        </div>
        <div class="col-xs-4">
            <button type="button" class="btn btn-default addButton"><i class="fa fa-plus"></i>
            </button>
        </div>
    </div>
    <div class="form-group">
        <div class="col-xs-5 col-xs-offset-3">
            <button type="submit" class="btn btn-default">Submit</button>
        </div>
    </div>
</form>

Jquery Code

$('#surveyForm').on('click', '.addButton', function() {
    var template = $('#surveyTemplate'),
        clone = template
        .clone()
        .removeAttr('id')
        .insertBefore($template),
        $employee = clone.find('[name="employee[]"]');

    $('#surveyForm').formValidation('addField', employee);
});
$("#surveyForm").on('change', '.user', function() {
    var value = $(this).val();

    $(this).find("option[value =" + value + "]").attr('disabled', false);
    $("select").not(this).find("option[value =" + value + "]").attr('disabled', true);
});

Note that when I click the add button, it adds a clone of this form.