Android > Media > com.whatsapp.
Anyway, there is a persisting issue with dual WhatsApp. Let's hope it will be solved very soon. Thank you.
The issue caused in Dual WhatsApp as recently WhatsApp upgraded its version and it changed the file path where all media files are to be saved.
Due to this change, Dual Messenger didn't sync media saved at new path and so this is causing problem.
Samsung is trying to solve the problem quickly by contacting WhatsApp team.