Hello Muhammad Nawaz,
Basically, this is kind of an expected behavior. When you have two equal instances of one and the same object, the selection does not know which of them to select.
What you may try to do is to clone the object you drag - in the DropQuery event you may create a new instance of the same object type and fill its properties with the values from the item you drag. Thus you will have two items with equal values, but they will be two separate instances.
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