In Incorrect section/category physical template detection discussion I've talked about physical and virtual sections and fact, that 2 urls exists to a single physical section.
At first this might not seem a big problem, especially if across a theme "use_section" parameter of m_Link tag is used, which forces url from "Structure & Data" section to be used. However if user manually guesses url to a TPL file, which is behind "Structure & Data" section url, then page will be shown too.
If google spider guess that url, then website could be banned because 2 different urls result in showing same page at all times.
I propose to automatically redirect (with 301 Moved Permanently http code) visitor to page url equivalent from "Structure & Data" section and put a notice into "System Log". This way developers would know that somebody still accesses old page url. And using HTTP_REFERER header they would know exactly who that might be.