Hy,
sorry a little late answer.
The filetype files are created when uploading an image and are important or necessary in case you don't use .jpg files for images.
There is a loader logic (don't know where exactly to find this) which loads the image id and the file extension, which is stored inside the fileType file. If there is no filetype file, then 'jpg' is used as default. The amount of filetype files should equal the amount of images since there is such a file for each and every uploaded product image.
G, M
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