Your plugin store normal file in upload folder and then copy to new file comment_name_file..
All plugins call WordPress media uploader functions, which creates the number of copy with specific size registered by the current active theme. This is being done automatically by WordPress. We're going to connect via hooks and disable registered thumbnail sizes for comment attachments. This will be added in next version.
Why plugin make jpg from pdf file.. Like thumbnails in posts. I get different size of pdf.. 1024 768 ..
This is something strange. The addon is not designed to do such things. I have no clue what's wrong on your end. Maybe you've somehow uploaded PDF file using Photo Uploading Option (but it should not allow you, maybe JS validation was disabled on your browser). The problem is the validation and restrictor function have not worked when you uploaded PDF using Photo Uploader. This may be due to Browser limitations or fornt-end JS errors cased by other plugins or the theme. Please debug your front-end errors or leave some URL to allow us check it.