There are many ways to duplicate clips in the Clips view:
Select a clip or multiple clips. Right-click in the Clips view and select Duplicate from the context menu.
Select a clip or multiple clips. Hold Command/Control and press D.
Right-click an unselected clip and choose Duplicate from the context menu.
Duplicating clips copies each selected clip and places the duplicates after the last clip on the same track. If you duplicate clips used in a blend or clips separated by a gap, the blend or gap is also duplicated.
If you duplicate an Animation clip that uses a recorded clip as its Source Asset, the recorded clip is also duplicated. The duplicate of the recorded clip only appears in your Project after you save the Scene or Project. For example, the following images demonstrates what happens if you duplicate an Animation clip named “Clip 2B” that uses the recorded clip named “Recorded (3)”.