That would be my opinion. You should only have one, no matter where you live. And paper is the better of the two, it lets water vapor through, and can hold some in extreme areas. The plastic just plain old stops it and lets it drip down, and where you have a hole in the plastic, tends to create more damage than it is worth.
Google vapor barriers, for your climate to get the real answers, this is an important part of your home that most folks do not pay enough attention to...then they cannot figure out "where is that mold comming from?"