Missing value from list pulled from array

When I hit my calculate button, the new lists with values pulled from the arrays are visible, but the second array is missing a value.The missing value is not always the same value. For example if I put in 1,2,3,4,5,6, it's not always the same number missing, it's probably the last value in the array, but I can't figure out where I went wrong. Here's the code:

$(document).ready(function(){
function copyarray(arraytocopy){
  var theCopy = []; // An new empty array
  for (var i = 0, len = arraytocopy.length; i < len; i++) {
    theCopy[i] = arraytocopy[i];
  }
  return theCopy;
}

function sortarray(arraytosort){
    arraytosort.sort(
        function(a,b) {
            return  Math.round( Math.random() );
        }
    );
    return arraytosort;
}

function checkarrays(newarray, oldarray){
    var swappositions = [];
    
    for (var i=0; i < newarray.length; i++) {
      if(newarray[i] == oldarray[i]){
        //alert(oldarray[i] + ' is the SAME!'); 
        swappositions.push(newarray[i]);
      }
    }
  
    var countsame = 0;
    swappositions.reverse();  
    for (var i=0; i < newarray.length; i++) {
      if(newarray[i] == oldarray[i]){
        ///alert(oldarray[i] + ' is the SAME!');
        newarray[i] = swappositions[countsame];
        countsame = countsame+1;
      }
    }
  
    for (var i=0; i < newarray.length; i++) {
      if(newarray[i] == oldarray[i]){
        //alert(oldarray[i] + ' is the SAME!'); 
        //swappositions.push(newarray[i]);
        var elementbefore = newarray[i-1];
        newarray[i-1] = newarray[i];
        newarray[i] = elementbefore;
      }
    }
    ///alert('test');
    ///alert('new array: ' + newarray);
    ///alert('old array: ' + oldarray);    
    //alert(swappositions.toString());
    //alert($.inArray( swappositions[0], newarray ));
    return true;
}

Array.prototype.randomize2 = function (){
    
    var oldarray = copyarray(this); 
    
    sortarray(this);
    var notthesame = checkarrays(this, oldarray);
  
  if(notthesame = false){
     //alert('sort again'); 
     sortarray(this);
     notthesame = checkarrays(this, oldarray);
  }
  
    
  //alert('new: '+this);
  //alert('old: '+oldarray);
  
  //alert('not the same!');
    return this;
};


function makelist(myarray){

    var list = '<ol>';
    var listitem = '';

    for (var i=0; i < myarray.length; i++) {
    
      if (/\S/.test(myarray[i])) {
        
        listitem = '<li>'+$.trim(myarray[i])+'</li>';
        list += listitem;
      }
      
    }
    list += '</ol>';
    //alert(list.toString());
    return list.toString();
    
}



function combinelists(ordered, random){

    var list = '<ol>';
    var listitem = '';

    for (var i=0; i < ordered.length; i++) {
    
      if (/\S/.test(ordered[i])) {
        if($.trim(random[i]) == $.trim(ordered[i])){
          listitem = '<li class="same"><span class="yourname">'+$.trim(ordered[i])+'</span> is matched with<span class="peersname">'+$.trim(random[i])+'</span></li>';
          list += listitem;   
        }else{
          listitem = '<li><span class="yourname">'+$.trim(ordered[i])+'</span> is matched with <span class="peersname">'+$.trim(random[i])+'</span></li>';
          list += listitem;
        }
      }
      
    }
    list += '</ol>';
    //alert(list.toString());
    return list.toString();
    
}



$('#ranGen').click(function(){
//function randomize(){
  
  var lines = $('#names').val().split(/\n/);
  var texts = [];
   
  for (var i=0; i < lines.length; i++) {
  // only push this line if it contains a non whitespace character.
    if (/\S/.test(lines[i])) {
      texts.push($.trim(lines[i])); 
    }
  } 
  
  
  
  
  var orderedlist = makelist(lines);
  //$( "#list" ).html(orderedlist);
  
  var linescopy = $.extend(true, [], lines);
  
  var randomarray = linescopy.randomize2();
  //alert(randomarray);
  
  var randomlist = makelist(randomarray);
  //$( "#randomlist" ).html(randomlist);


  var combinedlists = combinelists(lines, randomarray);
  $( "#combined" ).html(combinedlists);
  
  
}); 
}); 

textarea{
  height: 100px;
  width: 400px;
}

input{
  display: block;
}

.list{
  display: inline-block;
}

.same{
  color: orange;
}

.yourname{
  color: blue;
}

.peersname{
  color: brown;
}

<script src="http://ift.tt/1qRgvOJ"></script>
<h1>Get a random match </h1>
<p>Insert all your names into the textarea below. Each name should be on a new line. Hit the button to generate your matches. </p>
<form>
  <textarea id="names" placeholder="Enter list of student names here. Each name should be on a new line."></textarea>
  <input type="button" id ="ranGen" value="Go" onClick="JavaScript:randomize()"/>
</form>

<div id="list" class="list"></div>
<div id="randomlist" class="list"></div>
<div id="combined" class="list"></div>