In most cases as a "learner" you are required to have an attending physician oversee your activities. Duty hours are a potential issue if you are covering games in addition to your residency requirements. Typically the oversight is an attending on-call or in-person. That depends on the relationship with your attending. Bottom line is that it comes down to malpractice. If your malpractice covers you directly and you have discussed with them that you will be covering the games without supervision then great... If you are working under the attending, your malpractice is covered through the program and is considered an educational opportunity.
However, if you are a fellow and are board certified in your primary specialty, you can "moonlight" if your malpractice insurance will cover you. Although, if you are a fellow, you should have enough coverage that you are not out looking for additional opportunities.