Right now, you can import both LCC and DDC values separately, by varying the customization options from LLC and then to DDC. The internal db table keeps all of it. As a workaround, you can then swap from using LCC to using DDC in customization too.
Once I am finished with modifying all of my plugins for Calibre's upcoming use of Python 3 rather than Python 2, I will look at adding "both" as an option.
Added:
https://raw.githubusercontent.com/Jo...master/fdc.txt
DaltonST