title: How to prevent multiple instances of an Activity when it is launched with different Intents
body: <p>I've come across a bug in my application when it is launched using the <strong>"Open"</strong> button on the Google Play Store app (previously called Android Market). It seems that launching it from the Play Store uses a different <code>Intent</code> than launching it from the phone's application menu of icons. This is leading to multiple copies of the same Activity being launched, which are conflicting with each other.</p>
  
  <p><strong>For example,</strong> if my app consists of the Activities A-B-C, then this issue can lead to a stack of A-B-C-A.</p>
  
  <p>I tried using <code>android:launchMode="singleTask"</code> on all the Activities to fix this problem, but it has the unwanted side-effect of clearing the Activity stack to root, whenever I hit the HOME button. </p>
  
  <p><strong>The expected behavior is:</strong> A-B-C -> HOME -> And when the app is restored, I need: A-B-C -> HOME -> A-B-C</p>
  
  <p>Is there a good way to prevent launching multiple Activities of the same type, without resetting to the root activity when using the HOME button?</p>