duplicate photos

Each standard imported photo consists of:

an independent set of Catalog metadata referring to a stated external file on disk.

If you duplicate this external file and import it separately, then you now also have:

an independent set of Catalog metadata referring to a stated external file on disk.

If you create a virtual copy of either one, then this creates in addition:

an independent set of Catalog metadata referring to a stated external file on disk.

Notice the difference between these entities? that's right, none whatever... in practice. Everything you can conceive of so far as visual editing and virtual organisation is handled by the metadata that each one independently has. 

Unless you care about which external file is being referred to. If the content of two external files are identical, the only remaining possible areas of difference are: the file storage location, and the file name. There are many good arguments why these are the most restrictive and the least productive image attributes for library workflow. IMO the Catalog paradigm is precisely there to make the physical storage circumstances of the image file, into a mere incidental technicality. Not a useless one - for example I use a capture-date-based folder organisation whihc makes use of a permanent unvarying fact about each image. I am never going to want different variations on the same photo, to reflect different capture dates. And by distinguishing between multiple treatments from the same starting photo in metadata (for virtual copies) instead of some filename or folder based method, all can continue to refer to the same, single, constant stated file no matter what clever things I may otherwise want to do with them. 

Which version does your question refer to? Lightroom Classic or the cloudbased Lightroom?

You wrote about Lightroom CC but you posted in the LR Classic forum.

For Lightroom Classic an option is to do an export with the settings you'll see in the screenshot.

But I don't see the advantages over virtual copies. On the contrary, you need more storage space on the drive you saved your images.