Is there such a script?
I would call it "presets limitor".

But i don't know what you'd use it for since you already can export and import these settings to/from files.

Edit: my mistake, i tried importing/exporting and it didn't seem to do anything to my settings as if the import and export doesn't work at all

I was employing a script a while ago with an earlier version of Gimp, which would remove built up presets in some of the color and filter dialog's.
Over time these presets would build up and slow down cretin color dialogs and filter functions that use presets. When I looked at some of my presets, in a more recent Gimp Version. I noticed there seem to be only a hand full of presets available at any time. When before using an older version of Gimp. There presets would build up as you used the dialogs.
I was thinking that I had this script installed in my newer version of Gimp, but I don't remember what it called. I have many scripts and I don't really want to start look through them all. In hopes of stumbling upon it.

settings-cleaner.py
Ofnuts.

More info here - viewtopic.php?f=9&t=7299

You're The Man Rod, Thanks!

Just so happens I have that plugin installed.