The Clone Tool lets you create identical copies of a style prototype feature, including both its shape and its attributes, by clicking on the map. You can only use the Clone Tool with styles that have associated prototype feature shapes. Refer to Creating styles in the Palette for instructions on how to create these styles.
To use the Clone Tool:
1. Start editing.
2. In the ArcMap Editor, choose the Sketch tool and set Task: to Create New Feature and Target: to the layer you are working on.
3. Click the Clone
Tool button 
on the Scenario Sketch Tools toolbar.
The Scenario
Sketch Palette window will open automatically if it was not already open.
You may
wish to choose Thumbnails from the View menu.
4. Click on the style you wish to apply. The style must have an associated prototype feature shape. A highlight box will appear around the style you have chosen. If there is only one style in the selected layer, that style will be chosen automatically. The cursor will change to an image of the prototype feature shape.
5. Click once on the map in each location you wish to place a copy of the prototype feature. ArcMap requires that new features be placed within the horizontal and vertical extent of the layer being edited, which often translates to the extent of the currently existing features.
If you are not satisfied with one or more of your most recent feature placements, you can undo them one at a time by clicking on the ArcMap Edit menu at the top of your screen and choosing the Undo Add Feature. Typing Ctrl+Z has the same effect. Each Undo cancels one feature placement. After you have applied the Undo command, you can Redo from the same menu or by typing Ctrl+Y.
To commit your changes, choose Scenario 360 Stop
Edit 
or choose Stop Editing from the ArcMap Editor
menu and answer Yes when asked whether you want to save your changes.
To discard any changes made since you started editing or saved edits,
answer No. Ending
the edit session will also end the Clone Tool session.
To end your Clone Tool session without ending your Edit session, click on another editing tool.