Jpeg EOF

I'm trying to find out where the JPEG file ends, mainly to find out whether there's any information appended to the end of the file. I've tried searching for the EOF (FF D9), but to my surprise, this is repeated multiple times in the file in 1 out of 5 files.

Is there a way to safely determine where the JPEG file ends?

So there can't be sequences FF,D8 FF,D9 anywhere in JPEG streams? Why did they do it? Simplicity of parsers?