Sorted data has lots of missing files

I ran the tool on a PhotoRec recovery that contained 33,152 files and 153GB of data. The sorted output from `recovery.py` brings this down to 27,881 and 138GB - a massive loss of over 6,000 files and 20GB of data. What is it that recovery.py does that could have resulted in the loss of these files, and can it be fixed?