Did some experimenting, and it looks like Hydra Heads doesn't exactly seem to play well with the armor averaging system that was implemented late last year.
https://steamcommunity.com/sharedfiles/filedetails/?id=1655837714
Here's me with 2 heads, haven't had any cut off, regrown, or cauterized. That Knollworm Skull should be receiving an AV penalty because I don't have anything on my second head, but that's not the case. (AV and DV penalties are indicated by red #'s just fyi)
https://steamcommunity.com/sharedfiles/filedetails/?id=1655837737
Here's me with the Knollworm Skull and a Wide-brimmed Hat. I should be receiving a penalty on both for not having equal stats on either.
https://steamcommunity.com/sharedfiles/filedetails/?id=1655837746
Finally, here's me with the Knollworm Skull and a Leather Cap. This is where I shouldn't have an AV penalty, but clearly I do. I don't know how it's rounding those numbers, but something is definitely not right here. I haven't even tried experimenting with more than 2 heads or what happens if a head gets cauterized, there's no telling how far down the rabbit hole this goes. I urge Eboreg to take a look at this and figure out what's happening. Who knows, it's possible this has been contributing to those corrupted saves.