People were smarter than we think "in the past." Here's astronomical calculating device created hundreds of years before the Greeks supposedly came up with the idea (about 100BC).
http://apod.nasa.gov/apod/ap110109.html
If I can't find evidence that the offset cylinders are wrong, the right thing to do as an "archivist" is to keep this feature. Plus, it's a bit of a novelty.
But since actually instances of the Benz Bz III still exist, it would be a simple matter of just looking at one to discover the truth.
Brian, thanks for the Daimler manual. I'll see if I can skim through it for clues later today.