In OL the weight is locked out over head at the end of both the snatch Snatch and the C&J. Proper alignment dictates that the weight is directly over the lifter's center of mass which for most people means that the chest and head are in front of the bar. Since the bar starts in front of the body, during the completion of moves the lifter shifts under the bar.
I'm not sure if the double dip you're referring to occurs at the beginning of your lift, or if you're initializing with a dip and then dipping again at the end. If it's the first then you are using bar rebound to assist your lift (although at 135 and 225 it wouldn't be much). If it's the latter then you are shorting the range of motion to complete the move. To be honest it's an assistance exercise and how you do it depends on what actual move you want to assist. If it's the press then you should be using as little leg drive as possible and completing with a long ROM press, and if it's the jerk you want to enhance use as much leg drive as possible and finish with a short ROM press.
The version of Rip's books don't matter if you want to squat Rip's way, but if you want to squat Westside, Metal Militia, Olympic, etc got to other sources.