No, on kung fu boards. Basically, there are forms that have allegedly been marked when they give a public performance. Also, it is alleged to have occurred in training videos, picture books, and other media.
It was supposedly done so, instructors of say Lo Meng's School of Hun Gar could tell if someone stole their version of let's say the Iron Wire form. Also, if an instructor suddenly started teaching a Hun gar form *cough* Shaolin-Do *cough* you can point and say hey, that is book learned my instructor changed those moves on purpose.
True or not is up to you to decide.
Thanks. It actually goes on within what I do today..especially with people videoing so much so easily. When publicly demoing a form a few things will be changed exactly for the reason you give..not for the reasons I was given for the Hung Gar stuff.