Nintendo downloaded a pirated version of Super Mario Bros ROM file and sold it back to its customers through the Virtual Console. They did not even bother to edit the file in a hex editor to remove the original pirates header.
It's even worse than that. If they took the INES Header out, it would not work in their virtual console because their emulation is based on that original INES-key version made two decades ago (in fact, all of the NES emulators are).
So they're using the pirates' version of the ROM dumps, and also the important parts of the pirates' virtual machine implementation. Can't comment too much on the ethics of that since they
are open-source IIRC, but still.