You can dupe everything (including antenna).
The system is, you must visit the places where you get the special items (antenna, wires, sparkplug, etc) a certain number of times.
For example, if you get 2 wires after one trip to the farm and dupe the wires so that you have enough to fill up the building in the settlement, it won't work because the game sees you've only been to the farm once to collect the wires. You must go back to the farm on every reset maybe 6 times or more. The game will then see that you've been to the farm enough times to have gotten the proper amount of wires necessarily to finish the buildings.
Hope that was clear.