Actually, if you look it up the two expressions are considered synonymous and both are acceptable. That happens when one "wrong" phrase is used enough for long enough that it becomes acceptable. I looked this up and one old example they give is, "It is impossible that I could care less," which of course is grammatically correct.The right term is COULDN'T care less.
And the maker has been named.
Another example of this, I believe, is "irregardless" instead of "regardless." Both are now accepted.