检测用户是否在浏览器窗口中删除了相同的文件两次

I want to allow users to drag images from their desktop onto a browser window and then upload those images to a server. I want to upload each file only once, even if it is dropped on the window several times. For security reasons, the information from File object that is accessible to JavaScript is limited. According to I want to allow users to drag images from their