There has been a news on 28.9.2015 Nvidia introduced dual Maxwell to chosen group of people, presumably journalists, behind closed doors. Since then, nothing new, i paid attention.
The only exception, more or less "local" journalist known by a nick OBR, surely well known around these boards, recently wrote an article on local HW site concerning upcoming Nvidia and AMD stuff, where he said there is no dual Maxwell coming.
Which was actually in direct contrast with that info from September the same site posted (although clearly took from another source). Bottom line, journalism at its finest.