Double Shooter for 2013 robot

[bEdhEd]

Team 701 is planning on making another 2013 robot for the Western Region Robotics Forum Cal Games competition in the fall. The main goal we have is to make a double shooter. I understand that team 2337 The EngiNERDs has a double shooter, and I'm not sure if there are other teams that have a similar designs. From the videos and pictures I saw, they have the shooters on top of each other and they are using pneumatic wheels. Our team is planning on having the shooters side by side using 4" polyurethane wheels, but the wheels will be on opposite sides, so it's just like a standard two wheel linear shooter, but with a second shooter next to it, just mirrored.

I would like to know if anybody else has tried a side by side double shooter, or any type of double shooter, and has had any success with it, or if it was a failure, I would like to know what was learned from that.