I could see the mistake scenario you describe happening, but if it was happening over a longer term... isn't it a little harder to justify?
It's so difficult that neither I, nor Marcus, nor anyone else to my knowledge has attempted to do so. (I hope you noticed my sentence "Either way, it's copyright violation, and needed to be fixed....)
Anyway, if you're asking if I think it credible for third-party borrowings to be checked into CVS multiple times without the committer quite noticing his failure to replace them, I 'd say yes.
Copyright © 2018, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds