There can be no double jeopardy if the first trial never happened.
Not only that, if the verdict wasn't approved by all of the jury then the verdict doesn't count regardless of whether it was read or not. In other words, mistrial means just that. I read another news article earlier that was trying to make it sound as if the one person was actually found not guilty but the rest of the defendants were involved in the mistrial. This simply is not true. They(the government)now have the option of a new trial or no trial at all. I would guess they will re-try them. BTW, in some states the jurors are polled individually just in case someone tries an end run like this foreperson tried.