Comment 4 for bug 863472

The most common scenario in which this case might occur would be when someone is updating their save-to-disk folder. I cannot see this changing to bug people about that, nor should multiple copies be saved automatically.

If calibre is overwriting a book with a later book that uses the same calculated template path, the solution is to change the template.

calibre has a powerful template language which is explained here: http://manual.calibre-ebook.com/template_lang.html

In this particular case, I would use the following template fragment in general program mode:

program:

in_list(
 field('Tags'),
 ',',
 'News',
 'save as news',
 'do not save as news'
)

Simply switch out the "save as news" and "do not save as news" for whatever appropriate filename fragment you wish. Presumably, if it is news you would use field('date') which contains the timestamp when the record was added to the library.
And if it isn't news, you would use '' leaving it empty.

This works because all news downloads contain the "News" tag.

For multiple book records with the same author-title set, the other possibility is book duplicates, which are their own problem, and can nevertheless be saved separately by appropriate manual tagging.

Problem solved?