Shift+Clone is the primary way to duplicate objects in 3ds Max.
To clone an object or selection, hold down the Shift key and drag during any of the standard transform operations: Move, Rotate, or Scale.
To Shift+Clone an object:
As you drag, a clone is created and selected; it is now the object being transformed. The original object is no longer selected and is unaffected by the transform.
When you release the mouse button, the Clone Options dialog appears. Change settings in this dialog or accept the defaults, and then click OK.
Shift+Clone uses the Clone Options dialog for any transform you choose.
You can animate any Shift+Clone operation. See Animating Shift+Rotate and Shift+Scale.
Cloning objects with Shift+Clone requires transforming them at the same time, by moving, rotating, or scaling them. In some cases, you might want to clone an object without transforming it in any way. The Edit menu Clone command gives you this option, which lets you create only one clone at a time.
To clone objects without transforming:
Clone. The Clone Options dialog appears. This is the same dialog used with Shift+Clone except that there's no Number Of Copies setting. The Clone command lets you create only one copy.