The Duplicate tool creates a copy of a selected element that you can then position where you like on the current location.
To duplicate an element:
Select the element to copy.
Right-click and select Duplicate, or select Edit > Modify Elements > Duplicate.
Select a base point for the copy movement. Typically you would select one of the element's grab handles, but you can click anywhere in the drawing. The base point is simply a reference point used to define the move distance.
Select the point you are copying the element to. You can do this by moving your mouse and then clicking to insert the copy, or by typing a distance and direction in the Commander.