I must not be understanding the question. Doesn't it matter how many people there are in the first place from whom to choose? There could be 11 or there could be 1000. Looking at the extreme example, if there are only 11 people to choose from, then it would take ZERO shares to elect 2 members -- those eleven people are shoe-ins.

For all practical purposes, we can assume there are 12 candidates.  If there were only 11 candidates, then there would simply be no need to vote.  On the other hand, let's say there are more than 12 candidates.  If we want Candidates A and B to be elected, the opposition would have to make sure at least 10 candidates got more votes than either A or B to keep one of them from being elected.  Since it would be silly of the opposition to spread their votes thin, they would concentrate on only 10 candidates.  So there are only 12 candidates worth considering: A, B, and the 10 that the opposition has chosen.

I worked the problem based on this assumption, and I got that 833,334 shares were needed to secure both candidates' elections.

[NEAS: Correct; to be certain we can elect a director, we assume there are 12 or more candidates and determine the shares needed.]