"Card Magic for Amateurs and Professionals" by Bill Simon has an in-depth chapter on how to learn the second deal, along with a few tricks using it. Highly recommended!
Daryl's Encyclopedia of slights Vol. 1 is quite good. Daryl is a good teacher and very thorough. Sankey teaches it as well but I can't rembember which video.
Martin A. Nash's Sleight Unseen and Simon Lovell's Second to None are also good, for the Lovell book make sure to get the diagrams (they are separate but necessary).
Revolutionary card technique has a whole section on seconds. However, this is a rare book and out of print now. Definitely worthwhile if you can get your hands on it though - local magic society/friends may help you - if you're in the Durham area I'd be more than happy lol.
Am I the only guy on the planet that does not use a second deal? I can't even think of a single effect that utilizes one.....I am not saying they are not needed, just never needed one myself! Can you guys give me the name of a few "mainstream" effects require them?!?!?