Does WhatsApp duplicate media files? Whenever I receive or send a media file via WhatsApp, it is stored in WhatsApp/Media/.

Is it ever stored anywhere else as well? (perhaps depending on configuration of WhatsApp)

I want each WhatsApp chat media file and document to be stored only once in the whole directory structure (for a cleaner administration, and to save space). I am not referring to the same file sent/received many times.

Following instructions in https://www.whatsapp.com/faq/en/android/30031687, I placed a .nomedia file in each of the directories in WhatsApp/Media/ (WhatsApp Images, etc.), and in the respective Sent subdriectories.
With that, they do not show up anymore in the Gallery, so this suggests that the answer to my question is No.
Whatsapp is using peer to peer networks and hence its duplicating files to ensure its availability even though its deleted for one user. But its a bad concept and it junks your mobile. A mapping method should be used to avoid duplication.