The idea was to approach another company and ask them for permission to use theirs. Legally call it product placement. Now it's advertising. Surely that can't dilute the trademark.
* Would an average person look at a copper-and-black battery and think "this is a Duracell battery?"
* Did you try to stop people from using your trademark?
No, we made a deal with them to place our product in their game to make the average person even more aware.
The batteries in Factorio would be product placement ONLY if they were labeled "Duracell" battery. That means what Factorio and many other games did was not product placement, because they give no credit to Duracell for owning this design. IF someone does not know Duracell, they can't find out about their existence from any of those games.
But come on. Naming all of the batteries "Duracell battery" in Factorio makes no sense because 1: They are not being manufactured by Duracell 2: They are rechargeable unlike Duracell. This is Factorio, not the real world.
Clearly, if those questions are serious (which I'm finally convinced they are) there is a motive for Duracell to attack
Factorio for using the design, and for Factorio to back down from a fight that costs them time and money. Trademarks exist to prevent copying and stealing of popularity. That's reasonable. It would be confusing to see copper-black design on batteries other than Duracell's in real life for sure. (Not that I would be deceived.)
Here is my next question: Why would Factorio, or any game really, have an effect on what people think of real batteries? Virtual is not real. Everyone knows that.
(Okay, stop answering these... because we are going off-topic into the depths of recursive questioning.)