api.activity.create incorrectly adds id parameter for second activity

See http://forum.civicrm.org/index.php/topic,23084.0.html :

"Found what looks like a bug in api.activity.create in Civi 4.0.8 . I'm passing an array of 2 activities. The first is an update so I'm passing an id parameter. The second is a new activity, so I'm not passing the id parameter. However api.activity.create carries the id parameter over to the 2nd activity, so this acts as an update too. The net result is that the 2nd activity overwrites the 1st activity instead of creating a new one."

• further details in forum post.