Carl Hansen sofa  

No.  The SalesCo companies (Carl Hansen, Andreas Tuck, AP Stolen, RY Møbler, and Getama) had their specialties.  Carl Hansen was the first company in so there is one exception to the rule, which is the sideboard that Carl Hansen produced, but otherwise Carl Hansen did unupholstered chairs.  Tuck did tables and desks.  AP Stolen did fixed upholstered chairs (i.e. high end upholstery).  RY did case pieces, with a little overlap in the desk department.  And Getama was the factory maker who did loose cushion lounge seating (loose cushions being low end upholstery by the standards of the day).  

What about this one ? 

@lexi @herringbone @cdsilva Here the mark, if genuine.

I also checked the Wegner book "just one good chair" and I did not find any trace of this couch.

My apologies ! I must have been really blinded to not recognize this as a Hvidt piece. This let me think that someone has intentionally posted an image that has nothing to do with the couch just to get more value, but why ? That couch itself is already quite a nice piece without the Wegner name ! 

I was gonna say, I just refinished a Peter Hvidt daybed and they look remarkably similar. lol

Well all it would take to make that Hvidt & Mølgaard sofa into a widely acclaimed Hans Wegner design is for many people to repeat it.  That is all the truth there is to many design credits.  The only thing that really keeps that from happening is the fact that both pieces are almost always marked. 

The question I asked (but didn't post) myself yesterday evening was: where on the design was that stamp?

have no idea, the add is gone. Maybe they just messed it up with various items they had. After all, I need to reconsider my knowledge about furniture if I can believe that sofa was made by Carl Hansen in the first place.

@Andersen Don't worry. You'd have to be a savant to remember the thousands of pieces that have been discussed here or in literature, given that many of them look similar in one way or the other.  You re knowledge is okay as it is. :))

thanks for your understanding @herringbone