Cannot remove duplicate item from ContentArea

Description

Steps to reproduce

1. Add duplicated blocks (multiple times) into a ContentArea of a page.
2. Trying to iterate through the items and remove them programmatically.

        private void RemoveAllContentAreaItems(ContentArea contentArea)
        {
            int contentAreaItemsCount = contentArea.Count;
            for (int i = 0; i < contentAreaItemsCount; i++)
            {
                try
                {
                    contentArea.Items.RemoveAt(0);
                }
                catch (Exception e)
                {
                    Logger.Error("Could not remove block from Content Area", e);
                }
            }
            contentArea.IsModified = true;
        }

Expected: Can delete items from a content area programmatically.
Actual: Get the following exception:

System.InvalidOperationException: Sequence contains more than one matching element
   at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source, Func`2 predicate)
   at EPiServer.Core.ContentArea.RemoveContentFragment(ContentReference contentlink)
   at EPiServer.Core.ContentArea.ModifyCollectionInternally(Action modification)
   at EPiServer.Core.ContentArea.OnContentAreaItemsChanged(Object sender, NotifyCollectionChangedEventArgs e)
   at System.Collections.ObjectModel.ObservableCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs e)
   at System.Collections.ObjectModel.ObservableCollection`1.RemoveItem(Int32 index)