// count function

function countElement(item, array) {
    var count = 0;
    $.each(array, function(i, v) {
        if (v === item) {
            count++;
        }
    });
    return count;
}

// create array from ips in the list
ipList = [];
uaList = [];
$('li.list').each(function(i) {
    var spans = $(this).children();
    spans[0] = $(spans[0]);
    spans[1] = $(spans[1]);
    ipList[i] = spans[0].text();
    uaList[i] = spans[1].text();
});
// check how many for each ip
$('li.list').each(function(i) {
    var spans = $(this).children();
    spans[0] = $(spans[0]);
    spans[1] = $(spans[1]);
    var ipText = $(spans[0]).text();
    var uaText = $(spans[1]).text();
    var count = countElement(ipText, ipList);
    //if more than one update class of span
    if (count > 1) {
        spans[0].addClass('i' + count);
    }
    var countua = countElement(uaText, uaList);
    //if more than one update class of span
    if (countua > 1) {
        spans[1].addClass('u' + count);
    }
});



<ul>
    <li class="list">
        <span id="ip0">127.0.0.3</span>
        <span id="ua0">SonyEricssonK800i</span>
    </li>
    <li class="list">
        <span id="ip1">127.0.0.3</span>
        <span id="ua1">Nokia3120classic</span>
    </li>
    <li class="list">
        <span id="ip2">127.0.0.1</span>
        <span id="ua2">SonyEricssonW580i</span>
    </li>
    <li id="s3" class="list">
        <span id="ip3">127.0.0.1</span>
        <span id="ua3">SonyEricssonK800iv/R1KG Browser/NetFront/3.3 Profile/MIDP-2.0 Configuration/CLDC-1.1</span>
    </li>
    <li class="list">
        <span id="ip4">127.0.0.1</span>
        <span id="ua4">Nokia3120classic</span>
    </li>
    <li class="list">
        <span id="ip5">127.0.0.2</span>
        <span id="ua5">SonyEricssonW580i</span>
    </li> <li class="list">
    <span id="ip5">127.0.0.2</span>
    <span id="ua5">SonyEricssonW580i</span>
    </li> 
    <li class="list">
        <span id="ip5">127.0.0.2</span>
        <span id="ua5">SonyEricssonW580i</span>
    </li> 
    <li class="list">
        <span id="ip5">127.0.0.2</span>
        <span id="ua5">SonyEricssonW580i</span>
    </li> 
    <li class="list">
        <span id="ip5">127.0.0.2</span>
        <span id="ua5">SonyEricssonW580i</span>
    </li> 
    <li class="list">
        <span id="ip5">127.0.0.2</span>
        <span id="ua5">SonyEricssonW580i</span>
    </li> 
</ul>



.u2 {background:orange;}
.u3{background:purple;}
.u4{background:brown;}
.u5{background:pink;}
.u6{background:gray;}
.i2 {background:yellow;}
.i3{background:cyan;}
.i4{background:green;}
.i5{background:red;}
.i6{background:black; color: white}