I'm not sure if you're at all interested in this, but if you are still trying to figure it out this may be helpful. Or if someone else comes along with the same problem, here's a work around.

I get the problem no matter if I'm using FF or IE but I haven't gotten the problem so far when I stagger the Date/Time by 1 minute. So if both articles are set with the date/time of 4/3 at 6:00 I will get the error. But if one has a date/time of 4/3 at 6:01 I won't.

I can live with that.