Duplicate content caused by incorrect analysis of URLs

Let's say that my module registers the path 'mypath' with a callback function and no callback arguments.
Then if I go to http://example.com/mypath and http://example.com/mypath/somepath and even http://example.com/mypath/somepath/andsomemore I get exactly the same page.
This is unless I'm smart enough to add if (arg(1)) { drupal_not_found(); } to my callback function.

I believe the menu system should run a check for unnecessary extra arguments in the path before calling the callback function, similar to the one above.