Swedenborg made reference to Dippel's 'heinous' experiments, and strange practices in addition to their fued over religious ideology - although he never explicitly mentioned what those were.. using cadavers was common place at the time, so it must have been something more substantial to warrant the reaction.

But equally legends and myths all evolve over time, often from a foundation of truth. The Bible/Jesus is an example of this.. people add (and alter) the stories over time and add new bits. So modern additions based more on rumour than fact are to be expected.