The IconPackager category is made only for .IP or .ICONPACKAGE files. The Dock Icons category was made for .PNG files. Since you only have .PNG files in the download, that is where this deviation is supposed to be.
Though a category icon package, what such icon package?! It is the collection icons-) that is more than one icons in one place, and be it a folder, archive, or *.ip a file this everyone will be ICONS PACKAGER. Sorry for my English, very bad speak for him