Here is the “issue”: Open the “Properties” panel, navigate to “Named views”, select one of the named views and then activate the tickbox of “show named view widget” to show its camera in the viewport. While that custom camera could be freely moved around (if a certain object was moved and the purpose is to keep the camera angle relative to the former), Rhino refuses to make a copy of if. The only way to make a copy of the selected named view is to right-click on its thumbnail and choose “Duplicate named view” from the pop-up window. While this is a usable option, it’s still a bit weird that the named view’s camera shown in the viewport can’t be directly copied via the Gumball or the “Copy” tool, even though virtually all other objects in Rhino could be copied that way.
P.S.: Also, when a named view is being copied and both, the original and the copy have their cameras shown, Rhino won’t tell the difference between them via the pop-up window called “Selection menu”. It would be helpful to display the exact name of the named view in the list, because Rhino shows “named view widged” for both.