[ruslan_mart]

var arr2 = ['0', '1', '2', '3', '4', '5', '4', '7', '8', '9', '4', '11'];

function getRepeatArray(array) {
    var newArr = [].concat(array);
    for(var k, j = 0; j < array.length; ++j) {
        for(k = j + 1; k < array.length; ++k) {
            if(newArr[j] == newArr[k]) array[k] = array[j] = 'no';
        }
    }
    alert(array);
}

getRepeatArray(arr2);