This has been discussed many times on designaddict (one thread is here: http://www.designaddict.com/forum/General-discussion/Common-Mid-Century-...)
Who designed the Moller 71 chair? We've always assumed Hovmand Olsen based on the vintage ad stating that, and the fact that the chair is SO similar to other Hovmand Olsen chairs (notably the one for Selig.)
I noticed that both Design Within Reach and the current Moller website list N.O. Moller as the designer, though, so I emailed Moller and presented them with the vintage ad. They told me they'd research it, and got back to me a couple of weeks later with this:
"We apologize for the delayed response.
Niels Otto and Arne Hovmand-Olsen were very close friends. It was Niels Otto that designed the model nr. 71. He was educated as a carpenter, and Arne was educated as an architect. Because no one really knew who Niels Otto was at that time, he asked Arne if he could use his name.
J.L. Møllers Møbelfabrik"
It would be great if this design mystery were finally solved. What do you think?