There is a bugreport in Debian BTS about qcad community generating erroneous lines on printing to file.
Two dxf files are provided, and using this files the problem is confirmed on 2.0.5.0-1:After printing to PS, additional/erroneous lines are generated.
Details (including output PS files) on Bug#519294. Patches from community are welcome
Thanks
[patch request] erroneous lines on PS export/printing
Moderator: andrew