[AlgolC]

Personally I would determine if Duracell are in fact looking to reimburse the full cost of the camera.
If they aren't then why bother?

You should get a free batterie out of it either way.

I'd assume they are considering they've said something about enhanced customer care for Duracell? Any idea how to confirm if they are replacing the camera without setting off alarm bells?

You should be able to just ask them straight up. Ask if they plan to reimburse you for the camera because if they aren't you don't want to send it and you would rather try to get it repaired.