If you insert a file as a picture, and the file can not be displayed as a picture natively FM will create thumbnail versions of that file.
jpg & png will be 1 file
PDF will get a jpg and png version.
You can prevent this by inserting the file as a file instead of a picture, or store a jpg or png version of that file.
In order to maximize your chances of getting helpful responses its not a good idea to put the complete issue in the title of a posting.