Hello,

I reviewed the stack trace and the exception is telling us that "an item has already been added to the collection".

This particular exception is thrown intentionally and there is no logic in our source code to stop a "loading frenzy" from happening, or to happen silently in other cases. In our particular case the load method would never add items more then once, hover there is no logic for this to ever be prevented. 

May I ask why you require to change the layout very frequently?

Although there isn't a viable solution we use the following code to have the exception occur less frequently:

pivotGrid.DataSource.Rows.CollectionChanging += AreaItems_CollectionChanging;
    pivotGrid.DataSource.Columns.CollectionChanging += AreaItems_CollectionChanging;
    pivotGrid.DataSource.Filters.CollectionChanging += AreaItems_CollectionChanging;
    pivotGrid.DataSource.Measures.CollectionChanging += AreaItems_CollectionChanging;
}

private void AreaItems_CollectionChanging(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
{
    AreaItemsCollection senderColl = sender as AreaItemsCollection;
    if (e.Action == System.Collections.Specialized.NotifyCollectionChangedAction.Add)
    {
        foreach (var item in e.NewItems)
        {
            if (item is IComparable)
            {
                foreach (AreaItemsCollection filtersCollection in senderColl.UniqueGroup.Collections)
                {
                    foreach (IAreaItemViewModel areaMember in filtersCollection)
                    {
                        IComparable member = areaMember;
                        if (member != null && member.CompareTo(item) == 0)
                        {
                            senderColl.CancelCollectionChanging = true;
                        }
                    }
                }
            }
        }
    }
}

Let me know if you have any questions.