LivePlan is designed to avoid having a chapter, section, and items in a section with the same heading. Each item includes a Do not print header option, which is set intelligently:
If a section contains only one item, and it has the same name as the section, the option will be selected automatically.
If you add a second item in that section, the option will be deselected, since the item-level heading will then serve a purpose.
You can also adjust this option manually. Note that once you do that, though, the app will no longer adjust it automatically. It will be up to you to make sure it's in the right state if you add or remove items from the section.
You can also avoid duplicate headings by changing the title of a section.