You can quickly locate media that appears more than once in a Final Cut Pro project using highlighted clip ranges in the timeline or the timeline index.
In Final Cut Pro, open a project in the timeline.
Do one of the following:
Choose View > Show Duplicate Ranges.
Click the Clip Appearance button in the top-right corner of the timeline, then select the Duplicate Ranges checkbox. See Adjust timeline clip appearance in Final Cut Pro for Mac.
Open the timeline index, click the search field pop-up menu 
at the top left, then choose Show Clips with Duplicate Ranges. See Show duplicate ranges in the timeline index.
Clips with duplicate ranges are highlighted with diagonal lines in the timeline and the timeline index.
In the Final Cut Pro timeline or timeline index, select a clip that has a duplicate range.
To navigate to clips containing the same duplicate range, do any of the following:
Use keyboard shortcuts: Select the original clip, then press Option-Command-Right Arrow to move the playhead to the next instance, or press Option-Command-Left Arrow to move the playhead to the previous instance.
Use the timeline index: In the Clips pane of the timeline index, select the original clip, then select one of the other highlighted clips containing the same duplicate range.
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