The caseback looks like the gen to me. Lange's have possibly the most beautifully decorated movements of any watch I have ever seen.
the first rep I ever bought was a Lange tourbillion, which I picked up on the streets of thailand for about $7. It kept (keeps) good time, and is a great looking watch. It is a fantasy design however, as Lange never made a watch that looked like that.
When I bought it I had never heard of A Lange & Sohne, and just bought it because I liked the look. I did not want a rolex rep, as I figured people would guess that it was not a gen. When I returned to london some of the guys at work who are into watches noticed it and made a really big deal. I tried to be low key and said, oh, it is just an old watch I have had for years. Later I googled it and saw what Lange's cost, and what Tourbillions cost, and actually stopped wearing it. Now I only buy reps that I could genuinely afford the gen of, as I found that quite awkward...
Still love Langes, and hope to some day buy a Lange 1 Moonphase.