I recently noticed that every time I publish a post with LW, it automatically creates several different copies of the same image in multiple sizes, for example: I inserted an image into my post called img-3449.jpg. This image linked to a larger version of itself. When I published the post, LW uploaded img-3449.jpg and it created img-3449-thumb.jpg, which is ok, but then it also created img-3449-150x150.jpg, img-3449-300x199.jpg, img-3449-thumb-150x137.jpg. So for every image I post, I get 5 images on the server, only 2 of which are actually used. The settings are for LW to just publish the photos using the Wordpress settings, not using blogger or flickr or windows live etc, just the native wordpress content/uploads folder.
I've looked around through all of the forums but I don't see a mention of this anywhere. I've installed LW on multiple computers and posted to multiple blogs and it does this same thing with all of them.
Windows Live Writer uploads 2 images. One is the -thumb that is shown in your post, and one is the larger version that you see when you click the image.
Wordpress is generating more images at different sizes after Windows Live Writer uploads them.