You can not instantiate the GridViewDataColumn directly in your code. You can make your implementation of a column and inherit the base GridViewDataColumn. If you mean to clone data of a column, you can create a new column and setup the FieldName to be the same like some existing column in bound mode. This will automatically show the same data.
If RadGridView is used in unbound mode when you create a new column, you must iterate over all rows and manually set values for the new column using data from the existing one.
Registration for Q2 2011 What’s New Webinar Week is now open. Mark your calendar for the week starting July 18th and book your seat for a walk through all the exciting stuff we ship with the new release!