media using extra disk space on my server

hello everyone 🙂

whenever i upload a picture in my media it gets upload in many different sizes . i know its making different thumbnails. and its using extra disk space on my server. before some days my total disk space was used about 500 mb. but now i just checked my disk space usage on my server it more then 5 GB. just bcoz whenever i upload a picture it makes more then 10 different thumbnails. and its using to much extra disk space on my server.
before in my setting >> media >> this chek was on …Crop thumbnail to exact dimensions (normally thumbnails are proportional)…
but now i just turn this check of. but i dont think so it solve my problem. still when i upload a picture it make many different thumbnail.
i have just downloaded my uploads folder and i am attaching some screen shorts please have a look. and if you have any idea how can i decrease the same image thumbnails. will be very helpful. i think media just crop the thumbnails of every size and save them into the same directory. i just want media to not to crop the image just use the same image as thumbnail if it possible.

http://www.updatestube.com/wp-content/uploads/2012/12/media-duplicate.png

http://www.updatestube.com/wp-content/uploads/2012/12/media-duplicate-2.png

http://www.updatestube.com/wp-content/uploads/2012/12/media-duplicate-1.png

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