This is a convoluted matter, so forgive me if I talk in circles.
If a guy was to "look under the hood" at all the files on the SD card that goes with a scanner, you'll see several different types of files. Some might be f---.hpd, some might be s----.hpd with others being *.cfg.
The "S" numbers are part of the full database corresponding to state data.
Those "f---.hpd" files are Favorites List files that you created. Their numbers are based on the order of creation, so f---1.hpd is the first Favorites List file and if you've created 99, the last will be f---99.hpd. These F numbers are not repeated, my suspicion is they function like a unique index file number.
There is also a Favorites List configuration file, f_list.cfg that kind of brings or associates all those F---.hpd files together. As part of this file, there is the name you have given to the Favorites List that is associated with the f---.hpd file.
Because that Favorites List configuration file expects Favorites Lists files to begin with "F", trying to rename them may upset the apple cart.
So its best to let the actual Favorites List files use the file name that is assigned by the software that creates them and not try to fool the thing by renaming the hpd files. The scanner might resist these efforts and give you an unpleasant surprise.