I can't make my nesting do what you are experiencing. As I move the part in the nest, there is a solid yellow line for the part and a dashed yellow line offset from it for the gap between the parts. I can't find a setting to turn this off.

Does CAMduct do this with any of the default installed databases? I wonder if it something that has come through from your old installation.

You could try looking in the map.ini file for a relevant setting. Make a copy of map.ini before you edit it so you can easily go back to a known state.