Both answers are no.
The message list only shows the real contents of the headers, not translated stuff via the address book. Though I can imagine that that would be a nifty feature, I can also imagine that that would give scrolling through folders a rather heavy cpu-load on your system.

The easiest way to check for duplicate entries in the address book, is by disabling the 'Hide items if not explicitly selected' for all groups in your address book and then viewing the root of your address book while sorted on e-mail adddress.