|our knowledge of basic functions of transformation and duplication in Adobe Illustrator can save you a lot of time. You have no need for manual operation when Adobe Illustrator can do it instead of you.|
An object can be duplicated in Adobe Illustrator by copying it (Command / Ctrl + C) and pasting it to the front (Command / Ctrl + F) and to the back (Command / Ctrl + B). A new object will be located above or beneath our original object and the contours of both objects will match.
When you select the sublayer in Layers panel (Window > Layer) you will have an opportunity to double the object by selecting Duplicate "” in the fly-out menu.
By the way, I always work with open Layers panel, this allows following the changes and controlling the objects in the work process.It is often necessary to place a copy of an object in some new place. In order to move and double an object, keep Option/ Alt keys selected while moving.
You can read full version of this tutorial on Designmodo.com