<script>
function duplicate(){
 
var checked = [];
 
var i;
for(i=0;i<document.getElementsByName('form[one]').length;i++)
if (document.getElementById('one'+i).checked){
var one = document.getElementById('one'+i).value;
checked.push(one);
}
 
var j;
for(j=0;j<document.getElementsByName('form[two]').length;j++)
if (document.getElementById('two'+j).checked){
var two = document.getElementById('two'+j).value;
checked.push(two);
}
 
var k;
for(k=0;k<document.getElementsByName('form[three]').length;k++)
if (document.getElementById('three'+k).checked){
var three = document.getElementById('three'+k).value;
checked.push(three);
}
 
var l;
for(l=0;l<document.getElementsByName('form[four]').length;l++)
if (document.getElementById('four'+l).checked){
var four = document.getElementById('four'+l).value;
checked.push(four);
}
 
var arr = [one, two, three, four];
var sorted_arr = arr.sort(); 
 
var results = [];
for (var h = 0; h < arr.length - 1; h++) {
    if (sorted_arr[h + 1] == sorted_arr[h]) {
        results.push(sorted_arr[h]);
    }
}
if (results.length > 0)
	document.getElementById('Submit').disabled = true;
 
else if (checked.length == 4)
	document.getElementById('Submit').disabled = false;
}
</script>