ListView Xaml: IsGroupingEnabled and ItemsSource cause System.ArgumentException

When I was working on ListView, I kept get System.ArgumentException "An item with the same key has already been added."

So I did some experiments.

The problematic code:

<ListView  x:Name="TVListingListView"
                ItemsSource="CollectionGrouped"
                IsGroupingEnabled="True"
                GroupDisplayBinding="{Binding GroupKey}"
                GroupShortNameBinding="{Binding GroupKey}">

I can get rid of the exception by removing either "IsGroupingEnabled" or "ItemsSource". In another word, if only one of them presents, there is no problem. But if both present, an exception will be thrown.

I'm assuming it is a bug on Xamarin.Forms?

BTW, I'm using Xamarin.Forms 1.4.4.6392.