ShipSearch: prevent dupes in exact matches
ShipSearch: prevent dupes in exact matches

Fixes urbit/landscape#522

urbit/urbit,ngzax/urbit,ngzax/urbit,urbit/urbit,urbit/urbit,ngzax/urbit,urbit/urbit,ngzax/urbit,urbit/urbit,ngzax/urbit,urbit/urbit,urbit/urbit,ngzax/urbit,ngzax/urbit