nope, that's exactly the ecash magic! the mint never sees the ecash until it's actually spent. that means, when you restore unspent ecash (even though it is in cooperation with the mint) the mint does not know which token you're restoring.

you can imagine it a bit like as if the mint only has the encrypted token and you are the only one who can decrypt it. after decryption, the mint can't know what encrypted token it corresponded to.