Overwrites files that already exist when uploading, instead of storing multiple copies with unique filenames.
WordPress allows files to have the same name if they're not in the same directory. So,
wp-content/uploads/2013/11/pizza.jpg can live alongside
wp-content/uploads/2013/12/pizza.jpg. This plugin only deletes existing files if they are in the same folder that the new file will be placed in.
I do this as a way to give back to the WordPress community, so I don't want to take any donations, but if you'd like to give something I'd encourage you to make a microloan with Kiva.
I'm happy to fix reproducable bugs, but I don't have time to help you customize the plugin to fit your specific needs.