New code available. Free 1 Night DVD Movie Rental or Blu-ray ($0.30) or Game ($0.80) at w/Coupon Code - Redbox.com (Exp. 8/25/13)
Code: JR8WQLM
Seems that people had luck making up to 5 separate orders, but YMMV.
ETA: I just reserved 3 movies with no problems in separate transactions.