Yes, it happened to me just once, about 47 years ago. I was 13 or 14 at the time and because of my compass, was the only time in my life that I was really lost. It was 6 hours after dark when my Dad finally found me. Turned out my compass had reversed polarity without me knowing it. The next day I threw that compass as far as I could. Like you, now I always have two with me when I'm in the woods. I have also found that the electronic compass in my GPS is unreliable unless I am moving so I never rely on it.