How to avoid duplicated entries in Table of Contents

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When generating table of contents, sometimes we have to use master – detail to loop through all combinations. It is normal requirement to have a title for the topic and then with subtitles, which usually causes duplicated entries. Please see sample below
Before:
After:

Please download report specification for detail review. The idea is to make the production section conditional and only see it at the first page.

1. Create a query item runingcount =  running-count ([Product line])  
2. Create variable vShowProductSection to control that the title only show at the first time
3. Product Section title only renders at this first time
4. Make the whole line only show at this first time