从javascript和php获取价值在javascript中返回两个值

I'm a newbie in JAVASCRIPT and PHP. I'm sorry if this question is already solve in other problem. I just need the link that disame in my problem.This is my code:

All I want is their a code that xmlhttp.responseText return two value of my empnum and fname to their respective td id="erroremonum" and td ="errorfname".

All I get in this only the combination of two echo.

My table in index.php:

<tr>
<td >Employee Number</td>
<td>:</td>
<td width="150px"><input type="text" name="empnum" id="empnum" maxlength="4"></td>  
</tr>
<tr><td></td><td></td><td id="errorempnum"></td></tr>

<tr>
<td >Firstname</td>
<td>:</td>
<td width="150px"><input type="text" name="fname" id="fname" ></td> 
</tr>
<tr><td></td><td></td><td id="errorfname"></td></tr>


<tr>
<td><center><button id="submit" style="margin-top:20px" onClick="reg()">Submit</button></center></td>
<td colspan="2"><button id="cancel" style="margin-top:20px">Cancel</button></td>
</tr>

In my script:

function reg(empnum1)
{
var empnum = document.getElementById("empnum").value;
        if (window.XMLHttpRequest) {
        // code for IE7+, Firefox, Chrome, Opera, Safari
        xmlhttp=new XMLHttpRequest();
            } 
            else { // code for IE6, IE5
                     xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
                    }
                        xmlhttp.onreadystatechange=function() {
        if (xmlhttp.readyState==4 && xmlhttp.status==200) {
            if(xmlhttp.responseText)
            {
            document.getElementById("errorempnum").style.color = "Red";
            document.getElementById("errorempnum").innerHTML= "*Employee number is exist!";
            }
            else
            {
                document.getElementById("errorempnum").innerHTML="";
            }
        }
         }
      xmlhttp.open("GET","checkempnum.php?empnum1="+checkemp+"&fname1="+fname,true);
      xmlhttp.send();

}

Check empnum or fname is exist in database check.php:

$empnum = intval($_GET['empnum1']);
$empnum = mysql_real_escape_string($empnum);
$fname = strval($_GET['fname1']);
$fname = mysql_real_escape_string($empnum);

$checkempnum= mysql_query("SELECT * FROM systemuser WHERE employeenumber='{$empnum}'");
$num_rows = mysql_num_rows($checkempnum);
if($num_rows == 1)
{
 echo "employee number exist";
}
$checkfname= mysql_query("SELECT * FROM systemuser WHERE firstname='{$fname}'");
$num_rows1 = mysql_num_rows($checkfname);
if($num_rows1 == 1)
{
 echo "firstname exist";
}