AFAIK the older SuperPoxy and the newer UltraPoxy are different.
KlassKote says their hardener will work with SuperPoxy, but not UltraPoxy.
MECOA bought the rights to teh K&B line. IIRC, they have some UltraPoxy, but are selling off the stock and there will be no more.
There is KlassKote and Nelson Hobbies epoxy paints.
The Nelson stuff is water-based, and a System Three base product.