I've never found a specific tool for doing this, and it would be useful. One way round it is to go to Catalogue> All Photographs. This will show all the images in the catalogue. Then in the Library filter filter, under Metadata by file type, and also under Attribute filter for Master copies only. If you also order by creation date you will be able to scan through the thumbnails in the grid view. Duplicate images will now appear next to each other.
It's not perfect, and if you shoot a lot of bursts where telling images apart can become tricky it is harder. Still it gives you a pretty good idea if you have duplicate images, even where you might have changed the file name.
Filtering for file type might not always be appropriate, but I would think mostly you would be concerned about actual duplicates, rather than say a RAW and a PSD or TIFF. If you do need to look for more than one file type, don't forget you can Ctrl+click entries in the list to select multiple options. I only mention that, as it took me quite a number of years to realise you could do it.
Alan