Sometimes one rep might be on holiday (or generally busy) and not have the chance to look into it [the subject of the vote] & respond or might not be watching a topic with much interest but another rep might be available/more interested and therefore send in the vote. As long as they understand each org only has 1 vote (as clarified on the following lines) and the project reps co-ordinate (so as not to have conflicting views and if they do to discuss it within the project) I'd say this would be fine. If they both voted separate ways then both would be discounted until they sort out what the org wants to vote internally.

If they org cannot reach an agreement internally then they should just be abstaining anyway as the vote is the org's, not the rep's.