This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
AWT doesn't allow you to add the same instance of a component to more than one location in a layout. That's why the OK button is only added the first time. The Cancel buttons on the other hand, aren't the same instance, they just happen to have the same titles.