We are aware of this behavior and it is expected.
You are correct about the Microsoft treeview. But things are different here - our treeview is much more complex control and is entirely data driven. It is possible to support and this scenario, but it will involve a lot of code to be written in order to support this specific scenario.
The main difference between the WPF treeview and Telerik treeview is that ours can handle millions of records because of the use of virtualization - which means that we do not rely on the containers to keep the state of the items, because the containers are recycled all the time and can not keep any state. You will get the same effect when using the WPF listbox control which is also virtualized.
For the moment we can only suggest you not to use the same instance of your business object twice in the bound collection, we do not have plans to support this scenario.
the Telerik team
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