Terra's alternate is an Amano piece that was made for the original FFVI and never used, as is Kefka's alternate. You can see the full artwork here:

www.espritduo.com/images/terra_blue1.jpg

And a couple other blue Terra's:

www.espritduo.com/images/terra_blue2.jpg
www.espritduo.com/images/terra_blue3.jpg