Duplicate shots? Dupe detection. We don't have that. But we sort of have a reverse detection. Turn on "show used media ranges" and an orange line will appear under used areas of a shot in the event browser. So it helps determine if you've already used a shot as you're choosing a shot, but isn't useful for determining if a shot is duplicated in the timeline after the fact. Dupe detection would be a great, standard pro editing feature for the last 20 years, to be added back in, but Randy Ubullios didn't have a need for it in his scuba videos so it never made it into X.