Following questions all refer to examples presented in Implementing DDD

In article we can see from Figure 6 that both BankingAccount and PayeeAccount represent the same underlying concept of Banking Account BA

1. On page 64 author gives an example of a publishing organization, where the life-cycle of a book goes through several stages ( proposing a book, editorial process, translation of the book ... ) and at each of those stages this book has a different definition.

Each stage of the book is defined in a different Bounded Context, but do all these different definitions still represent the same underlying concept of a Book, just like both BankingAccount and PayeeAccount represent the same underlying concept of a BA?

2.

a) I understand why User shouldn't exist in Collaboration Context ( CC ), but instead should be defined within Identity and Access Context IAC ( page 65 ). But still, do User ( IAC ), Moderator ( CC ), Author ( CC ),Owner ( CC ) and Participant ( CC ) all represent different aspects of the same underlying concept?

b) If yes, then this means that CC contains several model elements ( Moderator, Author, Owner and Participant ), each representing different aspect of the same underlying concept ( just like both BankingAccount and PayeeAccount represent the same underlying concept of a BA ).

But isn't this considered a duplication of concepts ( Evan's book, page 339 ), since several model elements in CC represent the same underlying concept?

c) If Moderator, Author ... don't represent the same underlying concept, then what underlying concept does each represent?

3. In an e-commerce system, the term Customer has multiple meanings ( page 49 ): When user is browsing the Catalog, Customer has different meaning than when user is placing an Order.

But do these two different definitions of a Customer represent the same underlying concept, just like both BankingAccount and PayeeAccount represent the same underlying concept of a BA?

thanks