You might have downloaded same contents from different apps due to other social medias, when you download any file, photo or video and if you share it with someone, it might have made two copies on a separate folder. You have deleted media but it still might be in the cached folder.
When you are travelling or in any other occasions, you take multiple photos which are nearly similar Similar photos still occupies your storage and need to be removed to free more of your memory storage
Scanning & cleaning them from your device will help you release up to gigabytes of precious storage space from internal and external memory by using Duplicate File Remover App.