Find and delete DNG converted duplicates

I recently managed to recover my old hard disk where I found my original CR2 and NEF files that I had later moved to a new computer and converted to DNG to earn a little bit more disk space, deleting the original files.

I still kept that old hard disk with the original files but it suddenly stopped working a few years ago. So I only had the DNG files instead of the original camera-created raw files.

A few months ago, though, I managed to rescue that old hard drive with DDrescue and found my originals there. I was wondering whether there was any way to identify those duplicate DNGs in order to delete them and restore the original RAW files in their place now that disk space is not a problem anymore.

Thanks in advance.