Index: trunk/autoquest-core-usability-evaluation/src/main/java/de/ugoe/cs/autoquest/usability/tasktree/FilterResult.java
===================================================================
--- trunk/autoquest-core-usability-evaluation/src/main/java/de/ugoe/cs/autoquest/usability/tasktree/FilterResult.java	(revision 1199)
+++ trunk/autoquest-core-usability-evaluation/src/main/java/de/ugoe/cs/autoquest/usability/tasktree/FilterResult.java	(revision 1200)
@@ -45,10 +45,13 @@
     @SuppressWarnings("unchecked")
     public void addTask(ITask task) {
-        if (filterPredicate.apply(task) && !filteredTasks.contains(task)) {
-            filteredTasks.add(task);
-        }
-        else {
-            tasksNotMatchedFilter.add(task);
-        }
+    	boolean notFilteredYet = !filteredTasks.contains(task) && !tasksNotMatchedFilter.contains(task);
+    	if(notFilteredYet) {
+	        if (filterPredicate.apply(task)) {
+	            filteredTasks.add(task);
+	        }
+	        else {
+	            tasksNotMatchedFilter.add(task);
+	        }
+    	}
     }