Old images not deleted!

Hello, if I change the size in one of the add_image_sizes() in my theme, and use this plugin to regenerate those images, all the old images are kept on the server! For instance, say you install this plugin on a site with tons of images and you change the ‘Medium’ image size, regenerate, and look in your uploads dir, you now have the old and new medium image size = twice the storage being taken up!

I think AJAX Thumbnail Rebuild deletes all the image sizes (aside from the original) prior to rebuilding, that action would be preferable.

http://wordpress.org/extend/plugins/simple-image-sizes/