Okay, and if anyone wants it in python, here you go. It’s basically functionally equivalent (merge any number of .c2d files, with the objects from each nicely grouped), but writing it in wonderful python leads to much less obtuse source code. I figured a tiny Windows GUI utility was worth the effort, but I for one would much rather go back to my terminal. 
I threw it onto github, and I’m attaching it zipped here as well.
MergeC2D.py.zip (1.0 KB) – old version. Updated on github.