Some say the Mandela effect is evidence for the existence of parallel universes. In one universe Mandela died on Robben Island but in the one next door- which is ours- he didn't- and the people who remember him dying have crossed over from one to the other without noticing.
Parallel universes are respectable science, by the way. Moving between them isn't.
There was another story I read recently in which a woman woke up one morning and went to work only to find things had subtly changed and that she was employed in the same building but doing a different job.
I experienced what felt like the Mandela effect this morning when I read that Alec McCowen had died. Now I could have sworn that he'd been dead for years- not just because he's been out of the public eye but because I was sure I'd read the reports. I suppose I must have been mistaken....
And that's how people generally cope. They put the percieved anomaly down to a memory glitch and forget about it- and so the crack in reality gets papered over...