You first need to navigate to the new folder in the grid and then paste by right-clicking inside it. If you copy and try to paste before navigating to the new folder first, the file explorer will understand that as trying to paste in the same folder and will throw an error because the file already exists there. This is the behavior of the paste command in the RadFileExplorer (i.e. it does not respect the context of the item you right-clicked on and applies to the current folder).
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