https://www.reddit.com/r/civ/comments/58vmu8/extra_luxury_resources_dont_give_amenities_to/
I haven't gotten the opportunity to test his, but the guy gives screenshots of everything and explains it well. I'll copy and paste his post here:
"Since we learned how amenities work in a
livestream, people started saying that extra copies of the same luxury give amenities to more cities (1 copy = 4 cities. 2 copies = 8 cities and so on), but I never found where this info came from, since that's not what they said in the livestream. They say that the second copy is only for trade (like in Civ V), which later the manual confirmed (you can find it on steam, page 50, probably on the civilopedia too but I didn't check):
"Luxury resources provide a small bonus to the hex’s output and increase your civilization’s happiness by providing them amenities when improved. Only one source of a specific luxury provides amenities, shared with the four neediest cities in your empire. For example, if you have 2 Citrus resources improved around your capital, only the first will be providing amenities to your empire. You can choose to trade the second Citrus with another civilization for something else you need, like Gold, or another resource."
Since even
FilthyRobot said that the extra copy give amenities to more cities, I wasn't sure on what to believe, since it's not impossible that developers/manual are wrong (it can happen, games change a lot in production), but it's also not impossible that FilthyRobot learned how this mechanic supposedly work from someone and took it for granted, never actually testing it. So now that I have access to the game, I finally got to test it myself and sadly the extra copies is only for trade, like in Civ V. Prove:
I have:
2 teas, 1 Fur from improvements
If the extra tea copy is only for trade, I should have a total of 12 amenities form luxury resources spread among my 8 cities. If the extra copy give amenities, I should get 8 only from tea (one in each city) plus 8 from fur and wine, total 16. Lets take a look in my cities (don't mind the bad city and district positioning):
My Cities
Each city is getting:
- 2 Paris
- 3 Lyon
- 1 Rouen
- 2 La Rochelle
- 2 Bordeaux
- 1 Amboise
- 1 Nantes
- 0 Toulouse
Total: 12 amenities. 4 from tea, 4 from fur, 4 from wine and none from the second tea copy. I tested in more than one turn since the amenities are calculated at the end of the turn, still 12.
If anyone else want to test to see if I messed up and there's something affecting the result, I would appreciate that."
Sigh...come on Firaxis...