After months since I’ve booted up MCC, I logged in today and I got a Pelican’s load of achievements. Two of them were for beating Halo 4 on Legendary even though I haven’t even done so. I am not sure if someone from another Xbox I’ve signed into has done this or it is a glitch. I am not complaining about this delight, merely I wonder if this or anything similar has happened to anyone else.
P.S. I checked the missions list and all of them said I completed them on Legendary (Solo).