When bundling SMARTDAC+ GX/GP series' analog/digital modules with the main unit, can I select one of each (suffix code /Uxxxand suffix code /CRxx)?

No. Only one module option can be selected (either suffix code /Uxxx or suffix code /CRxx). If you need to add more modules, please order them separately. Note that if you do add additional modules, you must reconfigure the system.