It is a tool for icon pack designers/developers to copy and rename the icons into package_name.png name format.
It is developed to be used when converting icon packs into OEM themes, where the icons are often linked to applications by file names instead of appfilter.xml.
Due to my rubbish development skills, you should clean your appfilter.xml first, like cleaning duplicate lines, etc.
An appfilter cleaner tool developed by @danimahardhika CandyBar Tool: Appfilter Cleaner