I've never heard of a red Cavendish banana. Cavendish is very different from Jamaican Red. Another case of a mislabeled plant.

Steve

Or they call it that because by nature the Dwarf Cavendish has red splotches on the top until they get larger. Unfortunately nurseries are terrible about knowing anything about bananas. Since most plants don't have botanical names on the tags you have to trust them, which I don't. The best I have ever gotten out of any nursery owner is "the cold hardy, the regular and the blood banana." Luckily since the Siam Ruby has come around in years past they have nice printed tags because it's new and nobody knows what they are.