False positive backup folders, not actually existing?

Created by: illtellyoulater

For every website I scan Arachni gives me many backup folders (and I think it spends the majority of time with those requests and their processing). They usually amount to one hundred or more, basically they are multiple of the "real" pages because for any of those there are many backup folders.

But if I try to open them the servers just say 404 not found.

Example, just for a index.php, I get these backup directories in report:

http://www.domain.com/index.php%20-%20Copy%20(2)/ http://www.domain.com/index.php%20-%20Copy/ http://www.domain.com/index.php%20(4th%20copy)/ http://www.domain.com/index.php%20(3rd%20copy)/ http://www.domain.com/index.php%20-%20Copy%20Copy/ http://www.domain.com/index.php%20(third%20copy)/ http://www.domain.com/index.php%20(another%20copy)/ http://www.domain.com/index.php%20(copy)/

Strangely enough I saw a similar issue with OWASP ZAP which constantly reports the presence of many backup folders which just don't exist.. (can't remember if they had same names right now...).