getTasksAssignedAsPotentialOwner method of TaskService returns duplicate record

Issue

• Create a process with a User Task which has both actorId and groupId, Start a process and let it create a Task.
• Now call getTasksAssignedAsPotentialOwner with actorId and groupIds,

 List<String> groupIds = new ArrayList<String>();
 groupIds.add("PM");
 List<TaskSummary> list = localTaskService.getTasksAssignedAsPotentialOwner("john", groupIds,  "en-UK");
 System.out.println("list.size() = " + list.size());

• getTasksAssignedAsPotentialOwner() method returns duplicate record.

Is that a Bug and what is the workaround?