This 'thoroughness', if you can really call it that,
--has now reached the point of absurdity, and now borders on the just plain dumb.
Somebody who contributes info to the IMDB has, in the cast list, listed Jack Benny as not only playing Josef Tura, but also Col. Erhardt and Professor Siletsky!
It is Tura, the fictional character, who impersonates both Erhardt and Siletsky, not Jack Benny, and our contributor should be able to tell the difference.
This is the same poster who gets so thorough on other cast lists that they get incredibly confusing.