Cloning Sources
In the first section in the Clone Source palette, you can define multiple
areas of an image as a source from which to clone and/or heal.
Defining multiple sources.
The image above illustrates an example of when you might want to define
multiple sources. To save a source, click on one of the five source buttons,
and then Option + click (Alt + click) with either the Clone Stamp or Healing
Brush. That location will now be saved to that button. Now, select the next
button in line, and do the same in another part of the image. Once your
sources are loaded, you can quickly shift between them simply by clicking
the related button.