We aren't able to print the inner skin label when we have doublewall. I am not familar with CAMduct nor the labels but digging around, it appears that only one label set of labels can be applied at a time. As an example, for doublewall spiral duct, they are using a Label. Only one is produced when they want one for the inner and outer.
More than likely, you will have questions to get some clarity because I have no idea on the CAM stuff.
I am beginning to suspect that they are trying to use the wrong label for this but that is just a guess.