Comparing lat/long values in Google Maps V3

I have a map with a number of markers on it. Because of the way it is set up, one marker will always coincide with the centre of the map. I want to show a different icon on that marker to all the others.

The markers and their corresponding info box are defined with this function:

function createMarker(latlng, html, summary, photo1, photo2, thisLatlng) {
    var contentString = "<div style='min-height:150px'>" + photo1 + "<img src='/images/" + photo2 + "' width='225' height='150' align='left' style='margin-right:8px;border:none'></a><span class='title'>" + html +"</span><br>" + summary + "</div>";

    var marker = new google.maps.Marker({
        map: map,
        position: latlng,
        icon: thisicon,
        zIndex: Math.round(latlng.lat()*-100000)<<5
        });

    google.maps.event.addListener(marker, 'mouseover', function() {
        ib.close(map, marker);
        boxText.innerHTML = contentString;
        ib.open(map, marker);
        });
      google.maps.event.addListener(map, 'click', function() {
        ib.close(map, marker);
        });
    gmarkers.push(marker);
}

"latlng" is the a lat/long that is different for each marker. "thisLatlng" is the centre of the map and the lat/long of one specific marker.

My intention was to use something like this to determine the correct icon to use:

if(latlng===thisLatlng){
    var thisicon = icon1;
}else{
    var thisicon = icon2;
}

However it's not working as the "if" always returns false. I've tried

if(latlng===thisLatlng){

and

if(latlng==thisLatlng){

and I've also tried turning it the other way around with != and !== but they always return false. I've checked that the two values are equal by printing them one above the other and they look exactly the same (as they should be).

I must be doing something wrong, but what?