It's likely that those three Amiga songs were sampled by someone else and used in some other music that was subsequently registered with CD Baby.
Last year I made a video, 45 minutes long, where I diagnosed and fixed an old Sony PlayStation. Then at the end I turned it on to test it, and it was copyright claimed for the PS1 startup sound.
After lots of searching, I found that someone had sampled the PS1 startup sound and used it in some techno music. So, any YouTube video with the PS1 startup sound was claimed for copyright by the rights holder for that music track. I can only imagine how much they must have made in ad revenue from the millions of videos with that sound in it.
