NFT with IPFS

Hello everyone,
I followed the “How to Create NFTs Like NBA Top Shot With Flow and IPFS” tutorial using file storage via IPFS (Pinata), but there are things bothering me and I will need your help to clear up a few points.
The principle of NFT for example for the case of a .jpeg photo is to make this photo unique and non-reproducible otherwise it loses its meaning.
In the tutorial “How to Create NFTs Like NBA Top Shot With Flow and IPFS” the IPFS link is recorded in the NFT metadata and this poses a problem in my opinion, because these metadata are necessarily accessible to all (otherwise impossible to prove that the NFT in question does refer to a file), and yet if everyone has access to the information of the NFT it means that anyone could retrieve the IPFS link of the photo and mint another NFT pointing to this same link IPFS. So there is nothing unique anymore!
To avoid this it would be necessary not to give access to the IPFS link but by doing this how to prove to others that the NFT does indeed refer to the photo of the IPFS link ??

I thank you in advance for your help on this subject because for me in this way the NFT loses all its meaning which is to make a file unique in this example.