UsageRunning the plug-in require only 2 steps:
The result of the search for images is stored in 3 Collections in Lightroom, see screenshot below
Below I describe a typical workflow you could use to find and delete all derivative files. Of course, you can do also other things to these files.
Step 1 - Select the original photos
In this first step you select all original photos whose derivative file you want to find.
Step 2 - run the Find similar files plugin
In this step you search for all photos in your Lightroom catalog which have a similar name as the originals you choose.
The result of the search is stored in three collections:
Step 3 - analyze the search results
In this step you analyze all photos found. Again the metadata filter can help a lot. Apart from the first column "File type" you can choose for the other colums other information that can help.
First the "All_files_found" contains all photos found, both the originals and the derivative.
My this example it is easy to see that the derivative files are JPEG files.
Most interesting of course are the photos in "Different_from_Source" collection for these contain the files you wanted to find.
Step 4 - mark as "rejected" all photos for removal or deletion
Review all photos you found and mark as "Rejected", by pressing the X key, all photos which you want to delete or remove from your Lightroom catalog.
Step 5 - Deleting of photos marked as "Rejected"
In a Smart collection it is not possible to delete photos. For this we first go to "Catalog" panel and select the "All Photographs".
Next we select "Delete all rejected photos" from the "Photo" menu.
Now all "rejected" photos will appear, catalog wide!