I'm familiar with the idea that "duplicate concepts" indicate that you should have a separate bounded context, from, I think Martin Fowler's blog? This is actually partly what I was referring to when I said hand waving.
It's conceptually similar to answering the question "How do I know where the borders of Germany lie?" by saying "ask the first person you see if they speak German".
It also conflicted with a process I followed, which was to essentially create a team glossary and agree to semantically disambiguate terms which had multiple different meanings (e.g. linux user/website user instead of just user) and even just "ban" the usage of terms which got overloaded too much.
(I discovered that semantic collisions didn't just present problems in code, it often prevented you and your team from having coherent conversations).
This could, of course, then put everything we touched as a team into the same bounded context. Or not...?
>The example in the book given is the notion of a "Charge," which customer invoicing and bill payment departments might both use. But each department only cares about certain pieces of data of a charge
It sounds like they're essentially saying (not explicitly, but via assumption), that your software should follow conway's law.
Nonetheless, this example screams "bug alert" to me, since assumptions made by departments (and, as a consequence software systems) about what they should care about are where the really nasty bugs lie - frequently driven by misunderstanding between departments about terms (e.g. what counts as a user).