How to append a # to the name of a saved image automatically?

When you automatically save file unto the computer by one click download it is saved in a predestined folder. If you've already downloaded the file, or if you download a file with the exact same name; the file is saved with an appended number at the end; example: Save 1: image.jpg Save 2: image.jpg(2) If I try to save the image manually and the file already exists it tells me so and asks me if I want to replace it. If don't want the file replaced because it's a different image with the same name of another image; how do I set it to automatically append a # instead of prompting me to replace it. Appending numbers manually is kind of hectic once done daily. If appending is automatic, how do I set it to be automatic whence saving images manually?