@dzetland:
There do exist serious OA journals. They use a serious peer review procedure, and as opposed to predatory OA publishers, they often operate on a non-profit basis. They can survive because they are supported by institutions such as e.g. the IMS, see http://imstat.org/en/index.html
As for hiring or tenure committees, my experience is that duplicate publication is noted and does make a very negative impression. But I don’t know how representative these experiences are.
