Windlatch

Double doors don't like strong winds.

If you open the wrong door, the wind can catch it, rip it out of your hand, and slam it back against the building.

The Windlatch mounts above the door, with a "flag" panel sticking straight out from the building. Or, at least, it's straight out when the wind's not blowing. When it is, the panel is forced to one side (not all the way back against the wall; there's a stop to keep it from going flush & becoming useless). This slides a deadbolt into the door on the downwind side. The one that will still open is the safe one.

The flag might say "Please use other door" on both sides...