too long

I am able to return my first variable, however the second returns as undefined...any suggestions

here is my code:

function myFunction2(id, id2)
{
var target = document.getElementById('criteria_selected');
var value = document.getElementById(id).value;
var value2 = document.getElementById(id2).value2;
var myprint = '<input type="checkbox" value="'+value+',value2='+value2+'"/>'+value+' '+value2+' </br>';
$(target).append(myprint);  
}

level_completed and match_percentage1 are id's for 2 different drop-down boxes

<input type="button" name="add_level" value="Add" onclick="myFunction2('level_completed','match_percentage1');">

here is my php code in criteria_selected

                if (isset($level_completed) && isset ($match_percentage1))
            {
                echo '<input type="checkbox" value="<?php echo $level_completed,&nbsp&nbsp,$match_percentage1 ?>"> 
                    <?php echo $level_completed,&nbsp&nbsp,$match_percentage1 ?> 
                    </br>';
            }

I am trying to return the value as one checkbox

value2 is not a property of elements, use value.

var value2 = document.getElementById(id2).value2;

you can use jquery, simple and better.

function myfunction(id,id2){

var value=$('#id').val();
var value2=$('#id2').val();

}