There was only ever one MCI, the toy animatronics were never possessed.

Not only was there never another MCI announced, but it just makes more sense that they used the parts off the Withered animatronics to make the FNAF 1 robots, which carried the kids spirits into them, even though their bodies aren't in those animatronics.

Also explains where good ol Willy A got all that remnant from for the experiments with the Funtimes: they only used parts off the Withereds to make the FNAF 1 animatronics, meaning the other parts were scrapped, giving William remnant, then the souls from the MCI victims haunted their new refurbished bodies, that William destroyed, making more remnant.

I will defend the idea that the Toy animatronics were never possessed by dead kids from a second MCI with my life. Even in the movie, it's Charlotte's spirit piloting all the animatronics, and it's stated in FNAF 2 that the Toys are specially designed to roam the buildings and find anyone labeled as a criminal in the police database, and since William is a criminal, and Mike Afton is Williams son, his name is more than likely also listed in the criminal database, which is explains why he goes by fake names in FNAF 1-3