I decided to find out more about this amazing scientific discovery and artifact. See detailed description at:
https://en.wikipedia.org/wiki/Antikythera_mechanism
Dates I list here are approximate. The bits and pieces began to be found in 1901 in a 60 to 70 BC Roman shipwreck. Over the years other parts have been found in the sea including in this century, or in storage in various museums. Construction and callibration seems to have begun around 200 BC. Solar, lunar, and Olympic cycle calculations appear to have been part of the mechanism, among others. A part(s) dealing with planetary calculations appears to have not yet been found. Given this and other choice artifacts found in the shipwreck, my guess is that this was part of organized theft of Greek items of value by predatory Romans (governmental or private) as part of the overall conquest of Greece and their civilization.
The work appears to have been a collaboration among lead scietistists of that day and developed over time to try to integrate much of the astronomical science knowledge of that period. I would guess much like the importance and complexity of cooperation represented by our own NASA astronomical collaborations. I doubt extraterrestrials were involved. It would probably have required the very best craftsmen working with the greatest minds to develop and coordinate such complexity. As to were more than one produced? My guess is that some of the subunits probably had prototypes and final parts made, but this find probably represents the sole culmination of much work over time. I ask the question of you all, why is there only one Mona Lisa painting, one Sistene Chapel ceiling painting, or one David marble statue? Yes, there are copies, but only one original of vast cost and value.
At any rate, check out the link for a greater appreciation of the depth and range of Greek intellect and curiosity of that period. Not to be rediscovered and developed further until our own 1700s, around 3 centuries ago.
My guess is that the Mechanism, while extraordinary, was of minimal practical use. After all, in the ancient world, the usual means of navigation in the Mediterranean were simple instruments, portolan maps, and practical experience.
The larger point though is that the development of science and technology often involves people making connections between abstract intellectual theories, lab devices and playthings, and the real world as scientifically and technologically adept minds make practical innovations.
James Watt, for example, was an instrument maker at the University of Glasgow when he became interested in steam engines. He realized that contemporary engine designs based on Newcomen's steam water pump wasted a great deal of energy. Watt added a condenser that radically improved steam engines, along with an adaptation for rotary motion which greatly broadened its use. Thus began the steam age.
If the ancient world of Greece and Rome had more mechanical devices and more makers and craftsmen of machines and instruments they might have come up with steam power and begun that technological transformation much earlier. I think the Antikythera Mechanism is not so much as dead end as a lost beginning.
Eventually, through the Renaissance and practical innovations, Greek and Roman rationalism and practical needs endorsed by Christianity led to the rise of science and technology in the West. The Antikythera Mechanism tells us that with better luck, ancient Greek and Rome might have gotten there centuries earlier.