Something like this?:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Untitled Document</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<meta http-equiv="Content-Style-Type" content="text/css">
<meta http-equiv="Content-Script-Type" content="text/javascript">
<script type="text/javascript">
function filter(){
var root = document.getElementById('tab').getElementsByTagName('tbody')[0];
var oTr = document.getElementsByTagName('tr');
for(var i=oTr.length-2;i>=0;i--){
var oTx1=oTr[i].getElementsByTagName('td')[0].firstChild.data
var oTx2=oTr[i+1].getElementsByTagName('td')[0].firstChild.data;
if(oTx1==oTx2){root.removeChild(oTr[i+1])}
}
}
</script>
</head>
<body>
<table id="tab" width="400" border="1" cellspacing="2" cellpadding="2">
<tbody>
<tr>
<td>first-value</td>
<td> </td>
</tr>
<tr>
<td>first-value</td>
<td> </td>
</tr>
<tr>
<td>first-value</td>
<td> </td>
</tr>
<tr>
<td>first-value</td>
<td> </td>
</tr>
<tr>
<td>second-value</td>
<td> </td>
</tr>
<tr>
<td>second-value</td>
<td> </td>
</tr>
<tr>
<td>second-value</td>
<td> </td>
</tr>
<tr>
<td>third-value</td>
<td> </td>
</tr>
<tr>
<td>third-value</td>
<td> </td>
</tr>
</tbody>
</table>
<br>
<br>
<input type="button" value="Filter" onclick="filter()">
</body>
</html>