I don't think attending the same workshop is bad. If anything, it is a good way to discuss how effective the things learned in it were in the field. I've had it happen to me where I attended the same training and I just bombarded the trainer with additional questions even if they were outside of the scope of the current training. He was ok with it since he remembered our group. At the worst case, I just think of it as just being paid to relax and eat free food for a few days. It is just a matter of perspective and making the most out of the situation.