So, what should we do if there's a tie in the contest at the time the winner is selected?
(Vote for your preference, or add your own solution.)
Photo submitted last wins (on the principle that if it garnered the same number of votes over a shorter period of time, people had a stronger "like" reaction to it).
Photo submitted first wins. (The other one can, of course, win the next week, with the same advantage over newer contestants.)
Moderator picks. (This was, effectively, the previous tie resolution mechanism.)
Check for downvotes on the images (forbidden in theory, but happens in practice), and remove them from the count. If it's still a tie after that, move to the next option in the list.
Flip a coin.
Both photos run in consecutive weeks and next update is delayed a week