[mycologos]

Double-blind usually means something else in reviewing: the reviewer does not know who the author of the paper is, and the author does not learn who the reviewer is. Single-blind reviewing is when the reviewer knows who the author of the paper is, but the author still does not learn who the reviewer is.

As you mention, the problem with having two sets of reviewers is that it's hard enough for conferences like NeurIPS to find one set of qualified reviewers. Usually at least 1/3 of reviewers on any given paper produce a poor review, either because they don't care or because they really lack expertise. Complaining about this is so widespread that it even doubles as a sort of icebreaker for researchers, but nobody has a good solution.