Question

I came to pay a condolence call, and there people were talking about death and a brief return to life.
And there I heard several stories about people for whom a doctor had already signed a death certificate, and then they came back to life. One special case was about a young man who died, they issued a death certificate, and he came back to life, and today he is happily married with children, and his death certificate is framed. And there were several other stories, one of them about that grandmother who came back to life after two weeks, and more.
I remembered that a few years ago I was involved in an attempt to save a girl who drowned — resuscitation, helicopter, etc. — and the doctor signed off on death.
In the end she lived in the hospital for about 100 more minutes.
At the time I thought that that community doctor was not the sharpest pencil, but now that I came to offer condolences and heard a large collection of stories, some with names that people know and tell firsthand, it already seems to me like a real phenomenon.
And I assume this is not resurrection of the dead, but rather plain old screwups.
Is it possible that there is some systemic issue where living people are declared dead?
What about my Adi donor card?