Created attachment 382134 [details]
a shortened version of the source for SystemTap Tapset Reference

Description of problem:

When running 'publican clean_ids', it looks like publican assigns a new ID to each block tag based on information such as its parent tag, book title, chapter title, and nested <title> value. This is fine, except for two things:

- 'publican clean_ids' does not check whether it has assigned a non-unique ID. 

- as such, if another block tag is in the same chapter and has the same nested <title> value, it ends up with non-unique ID attributes, which fails validation and build.

Normally we wouldn't have sections in the same chapter sharing the same title, but clean_ids did this for <refsection> and <refsect1> tags (tried both). These tags are nested in <refentry>, and could be used for <title>Description</title>, <title>Values</title>, and the like. 

There could be numerous <refentry> items in a <chapter> or <reference>, all with their own <refsection>s or <refsect1>s for <title>Description</title>, <title>Values</title>, etc. This is the only instance I can think of where duplicate titles occur, but I think there may be other user cases.

Version-Release number of selected component (if applicable):

  publican-1.3-0.fc11.noarch

How reproducible:

  I tried it out using the attached book source, which contains a <reference> and numerous nested <refentry> blocks. 

Steps to Reproduce:
1. 'tar -xvf testbook.tar' ; 'cd SystemTap_Tapset_Reference'
2. 'publican build --formats=html --langs=en-US' -- build should be ok
3. 'publican clean' to remove temp XML and html files
4. 'publican clean_ids'
  
Actual results:
Running 'publican build --formats=html --langs=en-US' after clean_ids will fail, validation borks because of duplicated ID attributes assigned to <refsection>s. 


Expected results:

publican appends a unique number/string to each ID it assigns during 'publican clean_ids' (e.g. <section id="ch-ChapterOne-Title-123">). 

Additional info: