Possibly there is also a similar effect if the deleter hasn't refreshed his browser page.

Possibly. Specifically it would be if you (as the example) had retracted the page then refreshed it (to get the 'delete' button available to you) and then there is an arbitrary period of time after which you click the delete button without first refreshing again. (Untested, but those are the circumstances under which it would be at all possible if the code is not specifically designed to prevent it.)