The public "My daz 3d library" is the default location used by DIM.  I leave that location completely alone and let DIM handle it. Since V4/M4 is installed there, I guess I might have to install V4/M4 morph packs there, but so far I don't have any.

The User "My Library" is my old library. I have uninstalled all the DAZ products from this library, leaving only the non-DAZ products in this library.

I have a bunch of other Runtime libraries in different directories, probably about 20. I like to use separate runtimes for most free products I try, because many of them I discard after trying them. Having a separate runtime makes it easier to uninstall them by just deleting the directory.