templateFile vs. templateFile2

I was working on updating a template called “frontpage.php”, and cleverly thought I’d save some work in a new file called “frontpage2.php”. After updating the template file and everything worked, I updated one of the pages that uses that template. Then everything went wonky.

Turns out, when I updated the page that uses that template, it used “frontpage2.php” rather than “frontpage.php”. I can’t find anything in the Codex about using filenames like this. Is this a bug? or a feature I can leverage in future templates?