User blog comment:Dazabe/correction/@comment-5538801-20131207023706

As to why his mask changed, Amanda113122 has it right. However, another way we can distinguish between the two is by color scheme. Tuuli has a green mask and feet, and a turquoise body. Kongu has a turquoise mask and feet, and a lime body. The matoran in the picture from the movie's color scheme matches Kongu's. Therefore, we can assume that it is Kongu.