I have had success training twice a day at times. My workouts on Mon and Thurs were doubles with lower body in the AM and upper in the PM.....Tues was one workout focusing on cleans and assistance and Fri was one workout focusing on snatches. I got great gains and the added work allowed me to eat whatever I wanted whenever I wanted and stay lean.
If you want to try this type of training, try it, maybe you'll like it, maybe you won't, but don't let people discourage you just because it doesn't work for hardgainers (which you may not be) or because it could lead to overtraining (there is no such thing if you train intelligently) or because the magazines don't advocate it (they're about as useful as toilet paper).
Anyway, good luck, and if you want my program that i used let me know and I will post it.