I have done some contour rendering in previous versions so I thought I would try it. You're correct that a ghosted image of the part appears with the contour. I made several adjustments to the render settings, scene settings and the appearance. The only adjustment that makes a difference in the ghosting is the Gamma value in the render settings. An increased value will lessen the ghosting, however if the value is too high, the contour line quality suffers.
Setting the model to Hidden Lines Removed in the model window, then using the windows Snip-it tool actually does a pretty good job depending on your use of the image.
I had a play with that too - it does help but doesn't really give me the quality I'd like. Ultimately I ended up saving a series of images using File>Save As which gives you the ability to save good quality images but doesn't allow you to alter the line width (although this may be possible?)
Thanks for your input. I'm sorry to any SW Techs who read this (I'm surprised it got through moderation) but I am truly annoyed at some basic functionality issues I frequently come across. It's so frustrating.