In-Portal has 2 tags, that allow to use same template multiple times on other different templates:
- <inp2:m_Include - includes 1 given template
- <inp2:m_ModuleInclude - includes given template from each module
There is a problem with m_ModuleInclude tag in Admin Console, where he uses "core/" prefix to include templates from core module (see attached image). This works of course (otherwise whole "Structure & Data" section would be dead), but when you need to replace template, that is included (e.g. "catalog_tab" from core module), then you need to write "core/" before replaced template name.
What I've described might not be a bug, but because of "Sections" tab in "Structure & Data" page is loaded via ajax and is accessing "catalog_tab" (and not "core/catalog_tab", that was replaced) resulting page uses original non-replaced template.