are you aware that you can build double of every trade good or wonder?and the effect stack.with only your planets you can build double TG only if you have two planets building in the same time and that finish in the same amount of months.if you have a conquered planet you can build TG in double even if the two planets don't finish at the same time.it is really usefull.i got 2 the terraformer once(nice).in my current game i got two gravity accel and the effect stacked
Today on 1.05, I tried building two manufacturing capitals in two different planets that would each finish in 3 turns. One planet got the it and the other got nothing so at least for manufacturing capitals this does not work in 1.05.
If you have built, say a Manufacturing Capital and you capture a Planet that is building one, leave it alone and it will complete it.
That's with the latest version.
The case where you capture a planet is by design. You're allowed to capture enemy capitals and keep the benefit. If a captured enemy planet is building somthing you cannot build yourself, you're allowed to finish it. So if you haven't researched battleships, and you capture a planet that's producing battleships, you can leave the production unchanged and you'll get battleships. But once you cange it you can't change it back.