There are times when it is important to use “each” instead of “both.” Few people will be confused if you say “I gave both of the boys a baseball glove,” meaning “I gave both of the boys baseball gloves” because it is unlikely that two boys would be expected to share one glove; but you risk confusion if you say “I gave both of the boys $50.” It is possible to construe this sentence as meaning that the boys shared the same $50 gift. “I gave each of the boys $50” is clearer.