User blog comment:FishTank/Refining Your Editing Experiences/@comment-31714002-20200429175855

Video upload in UCP has a bug in which a YouTube video will replace another one without warning if they both have the exact same title. An easy workaround would be to rename (or now, "move") the existing video -- only problem is that a UCP move of a video will fail because it thinks the new filename is missing an extension. Hopefully this gets fixed soon because the video upload feature doesn't have a option to input an alternate title or automatically give it an alternate name like "title-2".