Some years ago there was a terrific trick explained in Genii, I made it up and have been doing it since that.It is a card trick and the effect is strong, the deck cuts itself at a chosen card.The trick had no known inventor, someone had seen it done by an unknown magician years ago.
To my great surprise at least two dealers sell this trick (no reference to Genii) one even put it out in manuscript form as a "new star of magic"!It was even advertised in Genii!
In the 70s there was a zig zag balloon trick described in the Linking Ring.About two months later small ads by do it yourself magicians started to appear in the Linking Ring where this zig zag balloon trick was offered.Quite a patetic case.
So read your magazines and dont buy things you allready own.
Im sure there are other similar cases. :confused: