There are duplicates of my external editors, so I cleaned out the dupes. I close Lightroom and restart, and all is good. When I try to edit a photo in, say, Topaz Impression, or any other plugin, there is just one selection for each plugin. Then I do the same a week later and many plugins are duplicated. Well, not exactly duplicated. The two versions have slightly different settings, such as one being JPEG (which is the one I saved) and the other TIFF (the new entry). So, I do it all again. Delete each of the dupes with the TIFF setting and all is good again. For a week. Then the dupes all return. I've been through this routine a dozen times with the same result.
Lightroom Classic has two methods of round-tripping an image via another application - that is besides, calling in an application for post-processing an export. These two methods are: External Editor, and Plugin - and they are presented and managed differently. So far as how options appear for using a given Plugin, that will be specific to each plugin which may well feel that it is just trying to be helpful!
External Editor method consists of either the automatic detection of Photoshop or PS Elements (whichever is present) that is to be passed an unsaved image, or user made presets which stipulate a certain application that is to be supplied with a presaved image of a stated file type, colourspace and bit depth.
I have never heard of external editing presets creating or re-creating themselves. But it is entirely possible that a plugin may be coded to ensure the presence of certain menu options, if they are ever found to be missing. Perhaps doing so only at next startup.