In my experience, it's often non-obvious when you have multiple "requirements" and when you don't. Except in retrospect when you realize you painted yourself into a corner.

Your experience is different, you always know when you have multiple requirements and should DRY, and when instead you have "incidental [or accidental] duplication" and de-duplciation would not be advisable and thus not be called "DRY"?

If so, I wonder what leads to our different experiences.