$tmpInstaller->install was executed twice on succes. This can insert …

…dublicate database entries.

See: http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=27802

libraries/joomla/installer/adapters/package.php

@@ -179,7 +179,8 @@ public function install()
 					$package = JInstallerHelper::unpack($file);
 				}
 				$tmpInstaller = new JInstaller;
-				if (!$tmpInstaller->install($package['dir']))
+				$installResult = $tmpInstaller->install($package['dir']);
+				if (!$installResult)
 				{
 					$this->parent->abort(
 						JText::sprintf(
@@ -193,7 +194,7 @@ public function install()
 				{
 					$results[$i] = array(
 						'name' => $tmpInstaller->manifest->name,
-						'result' => $tmpInstaller->install($package['dir'])
+						'result' => $installResult
 					);
 				}
 				$i++;