biblio database duplicate id in sets

[Gene Hovey <gene.hovey@teradata-ncr.com>]

 Hello, I am new to DocBook; please bear with me. I am looking for some 
help using Bibliography databases while processing a set of books. Using 
Bob Stayton's book, DocBook XSL: The Complete Guide, chapter 12, 
Bibliographies as a guide, I have sucessfully setup a "bibliographic 
database" where the bibliography of a single book uses empty bibliomixed 
tags with ids matching a biblioentry in the bibliographic database. I 
set the bibliography.collection param to point to the master 
bibliography xml file during the build.

Everything works when processing a single book. However, when I process 
a *set* of books where one or more books' bibliographies happen to have 
a bibliomixed element with the same id (to reference the biblioentry in 
the bibliographic database),

1) the set itself will not validate because of "duplicate IDs" (using 
xmllint) and

2) while chunking the set proceeded without error, Fop processing 
stopped dead with an error when it discovered duplicate IDs in the fo 
file (using xsltproc -> fo and Fop -> pdf).

I like the "bibliographic database" concept, but what I am missing to 
get this to work with sets? Am I limited to processing only at the book 
level?  Thanks in advance for any pointers.

Gene Hovey