如何在WPF中维护两个具有相同项目的可观察集合？

I have this observable collection where I add my items and bind with "Listbox" in the xaml. But I want to maintain a clone of this observable collection and bind that clone observable collection into that "Listbox" instead of original Observable Collection and add items into that cloned observable collection first and update Original Observable Collection with a button click. I'm using MVVM Light for by application. I have this observable collection where I add m