I mainly use AutoCAD for drawings and I always use dual dimensions because I communicate with people who use imperial and people who use metric.
I am loving using Sketchup to model and Layout to make design documents since it opens up a lot of options that I don’t have in AutoCAD but the one thing that is missing is the dual dimensions and it’s pretty critical for my work.
If you add this feature I would greatly appreciate it.
I copied the dimensions (fractional, in this project) and pasted them to another Dimension layer. I changed the units to decimal millimeters. In Shape Style I made the dimension lines transparent so only one set of dimension lines shows. Not as convenient as if it was a native feature but it’s easier than manually editing all of the dimensions to add the second set of dimension numbers and both dimensions are connected to the model so edits will carry through.