Welcome mikeb but a hack as you are using a libcdio not part of TC6 proper. Keep a backup in case something gets overwritten when using Apps for maintenance.
If you remove libcdio.tcz.md5.txt then the apps gui will not update libcdio.
Is this what you compiled
No, libcdio-paranoia-10.2+0.93+1.tar.bz2
Shouldn't libcdio.tcz be listed as a dependency of libcdio-dev.tcz?
Yes, I'll fix that as soon as the repo is back up.
How to split into a -dev extension?
You can do it manually - easy enough for small extensions - or copy the relevent section of one of the build scripts under repo.tinycorelinux.net/6.x/x86/tcz/src
Dev should include all .pc, .a, .la and .h files?
Yes, plus bin/*-config, aclocal/*.m4, vapi/* cmake/*, etc - to save space, you can leave out the .a libs - they are not required in the majority of cases.