Well here's the problem:

I'm on my Windows 7 machine and I had saved a sh3f file to my computer. Then I double clicked the file and SH3D opened with that library all imported. Problem is, there are now duplicates of some models.
However, when I went to: That particular library was not listed, only the ones that I had imported months ago.

So, where else might one look for libraries imported by SH3D?