If you indeed did realize that duplicate files hash to the same filename, why didn't you say so?

Because it is so obvious that it didn't even cross my mind to consider it worth mentioning.

Of course duplicate files hash to the same value. How could they not. (That's a rhetorical question!)

Instead, you say that the chance of collisions is remote.

Duplicate files hashing to the same value is neither surprising, nor "a collision". Not by any meaning of the term, no matter how contrived.

I don't treat OPs as idiots by explicitly stating such obvious truths.

Just as nobody--when they offer a line-by-line solution--explicitly states that if a large file contains no newlines; or a single line that is larger than memory; that the solution will fail.

Are we done with the meta discussion now?