DwD Studios

So as some of you may know, I primarily use BBF to run high-fantasy campaigns for kids and teens, with the rule of cool as one of my GMing philosophies. A few of them wanted to dual-wield or fire split arrows (i.e. 2 arrows). I've allowed them to do so by allowing them to roll twice, with a -10 penalty to each. What does everyone think of the penalty? Is it too small? I haven't quite calculated the statistical probability of getting a hit when multi-actions are factored in, but it seemed the most reasonable at the time when I was winging it.