"How does sightings work with more than 9 Pokémon close by?"

#PokemonGO: Hi travelers,If there are more than 9 types of Pokémon nearby, how does Sightings decide which Pokémon to show? Many times in my neighborhood, I see the sightings show 9 Pokémon. Could it be the case that there are more than 9 and I am missing (potentially) a rare Pokémon that does not show up in Sightings?Bonus points: I have read somewhere that the Pokémon you are tracking might not show up in Sightings when you enter/leave 70 meter area. People refer this to double backing? Does this mean that the Pokémon could potentially get erased from the Sightings although I am moving in the right direction? Can someone explain like I am 5?Thanks so much! via /r/TheSilphRoad http://ift.tt/2dszeRg