looks like you need to make the blue shadow it's own shape.... I don't know sign cut pro.... but if this helps:
in illustrator you can select both the red and the blue and use the pathfinder tool to "divide" or "trim". That will kind of stamp out the shape so that the red is it's own piece and the blue is its own piece in the shape of the shadow (not the shape of the two combined)…
In flexi, you can use the "combine" tools and use either "remove overlap" or "separate overlap"
Both are the same but different jargon based on the program
If there's something like that you can do in sign cut.... you could achieve what you need.
