WBLOCK & INSERT: This is a great way to copy a surface if you plan to design or manipulate the surface (it's also great for merged surfaces, pasting design surfaces into existing surfaces). All of the data that's used to define the original surface gets duplicated along with the surface making it independent from the original surface.
COPY: This option will work but you need to understand the functionality of the new surface. The surface gets copies but not the design data that made up that surface therefore it is still defined by the original entites. Meaning if the original design entities are changed or removed, your copied surface will update to reflect the changes.
COPY/PASTE: This option actually invokes the WBLOCK command and stores the surface in a temp file and places the temp file name on the clipboard. The PASTE option invokes the insert command therefore performing the same task as option 1 but without you having to save and define extra drawings. Keep in mind that the PASTE option will use the limits of the surface as the insertion point so for optimal results, right-click select Clipboard, Paste to Original Coordinates.
So now that we know the ways to copy a surface, what is the BEST way?
If you want the new surface to reflect the changes of the original surface use the COPY command.
If you want an independent surface within your drawing, best practices suggest that you make copies of the definition entities from the original surface and then just build a duplicate surface.
If you want to create your new surface in a separate drawing use the WBLOCK command for best results.
