Syncing a folder imports thumbnails as entries into the Media Library

When synching folders that already have thumbnail images in them, those thumbnails get imported as stand alone images in the Media Library.
This really pollutes the Media Library, and makes the should-be “thumbnails” subject to thumbnail generation themselves.

Is there any way to prevent images that follow WP’s thumbnail naming convention from being synched, and (thus) imported into the Media Library?
Ideally, all thumbnail images encountered should be linked/attached/bound to their similarly-named non-thumbnail parent images (providing an image with the appropriate name exists).

Of course, if no such (master/parent) image exists, importing the thumbnail could make sense. Especially since people may give some of their images names that resembling WP’s thumbnail naming convention (I know I have, before I was aware). Also, it could be useful if an orphan thumbnail is still being used on the site, even though all other versions have been deleted or abandoned.

Alternatively, is there a way to selectively synch specific images within a folder, rather than synching everything, as a way to prevent the importation of WP generated thumbnails after cleaning up our uploads folder?