I don't really think Mandela effects are really true. It's more just those things that get scrambled by people passing it along and making small changes. This can be seen in Sally Field's "You like me" Oscars speech or the berenstain bears name.
I think a couple of them can be explained by the effect Jim Carrey movies had on us all. Like in Ace Ventura when he punched that old dude with the monocle and said "you must be the Monopoly Guy!" Pretty sure that's why I remember Pennybags with a monocle.