[Solved] Spanning repeatable keys

In Elixir it’s quite easy with Enum.group_by/3:

iex> Enum.group_by(values, fn {key, _} -> key end, fn {_, value} -> value end)
%{
  "Caerus1" => ["Ramses Refiner", "Jupiter Refiner", "Jupiter Other",
   "Trader 13", "Cathode Supplier 4"],
  "Dionysus3" => ["Cathode Supplier 4", "Ramses Refiner", "Trader 13",
   "Jupiter Refiner", "Jupiter Other"],
  "Prometheus2" => ["Jupiter Other", "Ramses Refiner", "Trader 13",
   "Cathode Supplier 4", "Jupiter Refiner"]
}