The notarized version is a real will that is simply superseded by the latest will. The non-notarized version is also a real will and it is the last will i.e. the one that is honored.
Wills do not have to be notarized and do not have to be submitted to anyone. In most places they do have to witnessed or they “can” be legally deemed invalid, I’ve read. This latest one must’ve been witnessed or they let the witness requirement slide, as Michigan requires two witnesses.
Witnesses aren’t required, in Michigan, for a holographic will. The will must be dated, largely in the decedent’s hand writing and clearly reveal that it was i tended as a will.