Problem with code / duplicating field

[emhmk1]

I have a ajax script below which should get the info from the database with the option selected however when i select a name another select menu appears with the same details in.

<script language="JavaScript" type="text/javascript"> 
function display_data(id) {  
    xmlhttp=GetXmlHttpObject(); 
    if (xmlhttp==null) { 
        alert ("Your browser does not support AJAX!"); 
        return; 
    }  
    var url="aja.php"; 
    url=url+"?id="+id; 
    xmlhttp.onreadystatechange=function() { 
        if (xmlhttp.readyState==4 || xmlhttp.readyState=="complete") { 
            document.getElementById('employ_data').innerHTML=xmlhttp.responseText; 
        } 
    } 
    xmlhttp.open("GET",url,true); 
    xmlhttp.send(null); 
} 
function GetXmlHttpObject() { 
    var xmlhttp=null; 
    try { 
        // Firefox, Opera 8.0+, Safari 
        xmlhttp=new XMLHttpRequest(); 
    } 
    catch (e) { 
        // Internet Explorer 
        try { 
            xmlhttp=new ActiveXObject("Msxml2.XMLHTTP"); 
        } 
        catch (e) { 
            xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); 
        } 
    } 
    return xmlhttp; 
} 
</script>

and the rest of the code

<select onchange="display_data(this.value);"> 
    <option>Select pet</option> <?php
   $rows = $db->query("SELECT * FROM `".TABLE_ANIMALS."`");
   	while(list($id, $name)=$db->fetch_array($rows)){
		

        echo "<option value=\"".$id."\">".$name."</option>"; 
    } 
    ?> 
</select> 

<div id="employ_data"><?php 
if (isset($_GET['id'])) { 
   $rows = $db->query("SELECT * FROM `".TABLE_ANIMALS."` where id='$_GET[id]'");
		$row = $db->fetch_array($rows);
   
    echo "<table border=\"1\"> 
        <tr> 
            <td>Name:</td> 
            <td>".$row['name']."</td> 
        </tr> 
        <tr> 
            <td>Appoint Date:</td> 
            <td>".$row['age']."</td> 
        </tr> 
        <tr> 
            <td>Country:</td> 
            <td>".$row['colour']."</td> 
        </tr> 
        <tr> 
            <td>City:</td> 
            <td>".$row['breed']."</td> 
        </tr> 
        
    </table>"; 
 
}?> <div>

Any help would br great.