You can copy selected bay element(s) by dragging it (them) with your mouse to a new position.
Note: Copying bay elements with your mouse is convenient for quickly duplicating shelves or other panels. You can later specify precise position values for each element by changing their parameters. See Enter Bay Element Position.
Note: Back panels and side panels element cannot be copied as their quantity is fixed for each bay. You can however add dividers to create elements similar to side panels.