It appears that for every LUT file (.cube) you place in the "LUT" folder, Resolve creates a matching "shaperlut" file in the ".LUT" folder. Whether it's an internal LUT format native to Resolve, some kind of metadata, or something else, I don't know.
Note that on UNIX systems any folder preceded by a full stop like that becomes a hidden folder. So I'd say it's something internal to how Resolve works that you're not supposed to see.