aroidgrower

Their are a lot of forms of Xanthosoma violaceum is the one commonly called blue taro. Taro usually means colocasia but xanthosomas are commonly miss ID as them.
The form you have is Xanthosoma atroverins I sold a form and named one Xanth Blue giant years ago. It is a gian form of atroverins with dark blue leaves a bit different than the form you have their.

The Colocasia gigantea their are two forms. One form seems to be a sort of mutation that easily pups and is fairly cold hardy here. The other form is a much much larger grower and probably the reason the species has this name. It is not as hardy and rarely if ever pups.

I should add that their is a Alocasia on the market called Gigantea. This is one miss ID and it was later ID as a blue or purple stem Odora out of China. Its stems are purple and its leaves upright. It has shown to be somewhat hardy which is uncommon for us here up north with Alocasias.