Producing replicas of artefacts  is often touted as a solution to ownership disputes  – both parties can have a version. Of course it then raises a question of who gets to have the originals. Or, if both are equal then why either party would mind not having the originals.
There are many copies of the Parthenon Sculptures , made from a smaller number of first generation casts, but if they are indistinguishable, then one has to wonder why the British Museum has from time to time proposed that Greece should be completely happy with casts, when they themselves are unwilling to give up the originals.
A copy has its own history from when it was made & how it was made, but this is a completely different history to that of the originals. As evidenced in many cultural property disputes around the world, provenance is critical in many different ways. A piece of rock from the moon, even if of identical composition to one on earth has an inherent importance because of where it originated and what we can learn from that.
That said, copies have their own value, in allowing people to study items from a physical artistic point of view more easily & the prevalence of 3D printing is going to make this sort of research more commonplace in future.
Charlotte Observer 
3-D printer copying of sculptures: Is it legal?
By Ariel Bogle
Posted: Wednesday, Jan. 28, 2015
Almost every physical object, from a spoon to Edgar Degas’ famous dancer sculptures, can be scanned and uploaded onto the Internet as a file, ready for download by anyone with a desktop 3-D printer. But like the digitization of music and books before it, the migration of objects of art and design online brings with it the baggage of America’s frustrating intellectual-property regime.
A cast of Michelangelo’s famous 16th-century sculpture of Moses sits on the campus of Augustana College in Sioux Falls, S.D. Jerry Fisher, who lives in the area, decided to create a 3-D printable version of the artwork using photogrammetry – analyzing 2-D photos of an object and turning them into a digital 3-D model.
Only a few days after posting a downloadable file of Michelangelo’s “Moses” on the 3-D printing website Thingiverse in the fall of 2014, Fisher says he was contacted by a representative of Augustana College. They requested that he take it down, Fisher told me, citing fuzzy copyright and ownership concerns.
Despite feeling certain that the work was in the public domain, Fisher complied.
Peggy Kapusta, director of online communications at Augustana College, told me via email: “Mr. Fisher did not seek the permission of Augustana College nor the City of Sioux Falls prior to pursuing the 3D reconstruction technology or before offering (the 3-D model) to others. …
“In October 2014, we reached out to Mr. Fisher to express our concern over his actions in light of the fact that he did not seek permission from the college, the city of Sioux Falls or the families of the artist and/or the Fawicks (the family who donated the statue). At this point, Mr. Fisher made the decision to un-publish the 3D image file.”
It’s a baseless concern on its face, Michael Weinberg told me. He’s vice president of Public Knowledge, a Washington, D.C.,-based nonprofit concerned with copyright law. Weinberg said it’s part of the kind of knee-jerk assumption, common these days, that you need to get permission to do anything.
Overzealous colleges aside, Weinberg told me that the public domain is a foreign concept to many people, while copyright looms large over our digital activities, 3-D printing or otherwise. “One of the Internet’s lessons was that copyright is everywhere. That’s a reasonable shorthand to have, but it becomes problematic.” For a lot of people, there’s a vague alarm bell that goes off when copying something online. Given 3-D printing’s capacity to create high-quality replicas, this reticence can result in a chilling effect on how people engage with works of art that are free for all to reimagine.
The public domain artwork available to scan online is vast, said artist Cosmo Wenman, who has specialized in creating 3-D scans and models of classic sculpture. “Just about everything in the British Museum is unambiguously in the public domain. Millions and millions of cultural objects should be scanned.” Some museums and galleries are beginning to take the initiative. The Smithsonian has been making 3-D scans of certain objects available for download for a number of years, and the Baltimore Museum of Art announced plans in 2014 to release a scan of Rodin’s famous “The Thinker” to the public.