I think the idea is both are adding new files and also making changes to various files but his commits to the non-new files caused the conflict. Also, if both new files affect the same deliverable (like a DLL) then that could create a conflict in some cases (though I think that all depends on the build system).
Oooh, you just gave me a thought of mine! My bedside stand was a hand-me down from a college friend in the 90s. So I’ve been using that for close to 30 years now.