You have included the Google Maps API multiple times on this page
Remove the first line:
<script src="https://maps.googleapis.com/maps/api/js?v=3.exp"></script>You are including the Google Maps API twice.
Your problem is that, like others have found out, the duplicate script of the Google Maps. Please check the link below for working code.
http://jsbin.com/husahasu/1/edit
To render the map you need to specify its centre. It will not render without it.You also need to add css for your elements.Put this in the head of the document.
<style type="text/css"> html { height: 100% } body { height: 100%; margin: 0; padding: 0 } #googleMap { height: 100% }</style>
In my case I inserted link to the library twice, in the top page and before div.I delete any link and it's will work. You check links in your page.