If you are using WordPress on your server for writing blogs and using latest version of it then you might be having a problem with it, Every time you publish a blog which has images then you will notice that you had got a Thumb image.
This image has same size, and same resolution. Adding an extra image to server is not good even if you are on Unlimited hosting plan, some web hosting companies put some restrictions on file limit, so if you are having 2 images and one of them you wont use at all then why you should keep it on your server.
Well actually this problem only comes if you are using Windows live Writer for writing your blogs, its WLW who create your thumb image.
For instance just add any image on your WLW and then switch to Source mode and you will see that WLW has added a Thumb, with your image.
So if you wanna disable this Thumb creating feature then all you need to do is click on Image then move to Format and then select No Link or None under Link To Option.
That’s it, now you wont get any kind of extra Thumb image. Cheers.