There are many ways to duplicate objects in Illustrator. The simplest is to select an object (or objects), hold down the Option/Alt key, and click and drag. When you release your mouse button, you place a copy of the selected paths on your artboard (Figure 36).
Figure 36 Copying with the Option/Alt key.
You can also copy and paste selected objects by choosing Edit > Copy from the menu. Three paste options are available from the menu. In addition to the regular Edit > Paste, you can also paste in front or in back.
Illustrator allows you to manage stacking order as you paste. Edit > Paste in Front stacks pasted objects on top of other objects, and Edit > Paste in Back stacks pasted objects below other objects.
You can use the Copy and Paste commands to transfer objects in and out of Illustrator.