Please specify in bitvise as username including the domainname, thus either physics\…. or sterrewacht\…. because the default in the RDP tab uses the login credentials from the ssh login.
Also make sure the correct tunnel is setup:
If you want to make use of the double screen setup:
After that go to tab General and click “Save as..” and specify a filename, e.g.: Twoscreens.rdp Put the file in e.g.: My Documents.