They are totally different. They just have the same name. The Tonga toast at Konas is a piece of really thick bread, stuffed with bananas, deep fried, then rolled in sugar and cinnamon. It's soooo rich, but sooo good! The Tonga Toast at RFC is just regular french toast that comes with strawberries, sliced bananas, and walnuts on top of it and then they give you maple syrup to pour over it. Tonga toast at Konas doesn't come with syrup and doesn't need it and the bananas are warm and gooey inside the toast, not cold and sliced on top of it. Both are good, but I MUCH prefer the Tonga toast at Konas.
FYI: I haven't had it, but I believe Cap'n Cooks at the Poly, has Tonga toast like Konas.