Amro, yes, this is the specifics of the program. It copies the files to the working directory. And then it makes the conversion with the files. Because you can not rewrite the files themselves. This will cause errors in the work.
I know about this problem. And here very often they ask about it. But this is not my program, and so the author conceived. Therefore, it takes 3 times more space. You can certainly do everything differently and fix it, but I'm too lazy to do it.