Edit in JSFiddle

<!DOCTYPE html>
<html>
<head>
    <!-- Outbid Integration Start -->
    <script>
        (function (w, d, o, f, k, c, a, m) {
            w['OutbidTagObject'] = k;
            w[k] = w[k] || function () {
                (w[k].q = w[k].q || []).push(arguments)
            }, w[k].l = 1 * new Date(),
                w[k].cmd = w[k].cmd || [],
                w[k].config = w[k].config || {};
            if (c) w[k].config.ch = c;
            a = d.createElement(o),
                m = d.getElementsByTagName(o)[0];
            a.async = 1;
            a.src = f;
            m.parentNode.insertBefore(a, m);
        })(window, document, 'script', '//www.outbid.io/static/banners/v1.3/outbidtag.js.php?ch=www.twizl.com', 'outbidtag');
        outbidtag = window[window['OutbidTagObject'] || 'outbidtag'];
        outbidtag.setAutoTargeting = outbidtag.setAutoTargeting || function () {
        };
        outbidtag.adserverRequestSent = false;

        var OUTBID_TIMEOUT = 700;
        var googletag = googletag || {};
        googletag.cmd = googletag.cmd || [];
        googletag.cmd.push(function () {
            googletag.pubads().disableInitialLoad();
        });

        outbidtag(function () {
            googletag.cmd.push(function () {
                sendAdserverRequest();
            });
        });

        function sendAdserverRequest() {
            if (outbidtag.adserverRequestSent) return;
            outbidtag.adserverRequestSent = true;

            outbidtag.setAutoTargeting();
            googletag.pubads().refresh();

        }

        googletag.cmd.push(function () {
            setTimeout(function () {
                sendAdserverRequest();
            }, OUTBID_TIMEOUT);
        });
    </script>
    <!-- Outbid Integration END -->

    <!-- Load Google GPT.js script -->
    <script type="text/javascript" src="//www.googletagservices.com/tag/js/gpt.js" async></script>
    <script>
        googletag.cmd.push(function () {
            googletag.defineSlot('/1038998/twizl300x250atf', [300, 250], 'div-gpt-ad-1460505748561-0').addService(googletag.pubads());

            googletag.defineSlot('/1038998/twizl728x90hp', [728, 90], 'div-gpt-ad-1460505661639-0').addService(googletag.pubads());

            googletag.pubads().enableSingleRequest();
            googletag.enableServices();
        });
    </script>
</head>

<body>
<h2>Test</h2>
<h5>Div-1</h5>
<div id='div-gpt-ad-1460505748561-0'>
    <script type='text/javascript'>
        googletag.cmd.push(function () {
            googletag.display('div-gpt-ad-1460505748561-0');
        });
    </script>
</div>

<h5>Div-2</h5>
<div id='div-gpt-ad-1460505661639-0'>
    <script type='text/javascript'>
        googletag.cmd.push(function () {
            googletag.display('div-gpt-ad-1460505661639-0');
        });
    </script>
</div>

</body>
</html>