"Duplicate" rather than copy-paste would be a great idea. Already you can do it with a second GN window open (as noted in another comment) by dragging to the other window, dropping, then dragging back (even several times, if you want).

But why not allow the same facility without a second window? At the moment, dragging the "white box" in the same window looks promising... but disappoints by just snapping back when you let go. Why can't it simply duplicate? That would be a super time-saving feature.