Meanwhile I setup a 2008 R2, installed updates, conifgured (LAN etc.) and activated it. After that I cloned that VM to a Template. Now, no matter if deploying a vm from that template nor cloning that template and convert it back to a vm after that, seems to work for my purposes. After booting the template-vm it doesn't show lan1+lan2, but lan3 and 4. The"old" adapters and IPs are still there but don't show up. That's not too bad but unfortunately the system isn't activated any more. I didn't customize the vm while deploy/convert from template.
Am I doing something wrong or should I work with real clones instead to get a 100% copy of my 2008 server?