Hello,
spine-c has a file called Bone.c and our engine has a file called Bone.cpp. Default Visual Studio's (and probably many other IDEs') behavior is to put all compiled object files into a single intermediate directory so both of those files are compiled to Bone.obj which obviously result in linking errors.
Yes this is not a huge problem as it can easily be fixed in project settings but I think it would be a good practice overall to prefix spine-c runtime files with "sp" (spAnimation.c, spAnimationState.c, etc.) similarly to how you previously added a prefix to struct and function names. What do you think?