U.S. citizen working in Germany for a U.S. company

[norcal_sf 124]

Old topic, but I wonder if anyone else has run into this.  I work for a large multinational headquartered in the US.  I started with this company in Germany, work under a German contract, have never work for this company in the US. Every year they also issue me a W2 from the US which means I get two tax documents, a Lohnsteuerbescheinigung and a W2.  Can anyone explain why I get a W2?  I've always filed my German and US taxes in the past with just the information from my Lohnsteurbescheinigung when working for previous German-only employers.