It could be a very old ISO.
One of the 10 first releases ? (maybe Raving Rabbids ?? just a guess. Some iso had .bin, other .wii, raving rabbids had .wii)
These iso are scrambled (un-aligned for ISO9600 norm), they are RAW dump from a Wii game disc using a computer disc reader.
You need to unscramble it using Unscrambler 0.4, and delete the additional data using an hexeditor.
(version 0.3 worked better and didn't add the additional data, but I can't find it anymore on internet or my HDD. Someone kept it? for archive purpose).
To check if your ISO is scrambled or unscrambled, you can check the file size:
Wii single layered :
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If it's 4 699 979 776 bytes, it's unscrambled.
If it's 4 700 012 544 bytes, it's unscrambled with unscrambler 0.4 which adds an extra 32 768 bytes to the file (JESUS release)
If it's 4 736 698 368 bytes, it's in raw format and must be unscrambled.
Wii double layered :
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Unscrambled : 8 511 160 320 bytes
Scrambled : I don't think anyone ever dumped a DVD9 scrambled iso