ng-map showing two maps instead of one

Question

I am using This map library to show map in my website.

My html code for map is following:

<ng-map center="{{center}}" zoom="10" default-style="false" id="map">
</ng-map>

In my controller

$scope.center = "Manchester, UK";

When i load page it shows two map instance in map section as bellow.
I tried to reload map after add value to center as follow

$timeout(function() {
  google.maps.event.trigger(map, "resize");
});

But still it showing same.