As many have pointed out, CNN has *previously* included duplicate polls from individual pollsters. However, although their stated inclusion rules for this (5th) debate were clearly intended to be quite explicit, this is one point that they failed to include explicitly. They were clear about which polls would be excluded, but they don't actually say in the rules that any specific polls will definitely be included in the average.
If I were with the Paul campaign, I would definitely be arguing this point. Considering that the only thing holding him back in Iowa (as of 12/8) is an old, duplicate poll from CNN, this seems to me a pretty strong argument. I'm' not sure how likely they are to press the issue.
Of course, if another IA poll comes out showing him at 2, then even this argument won't save him.