1069: Remove tr8 string

Author: danhalson

config/locales/en.yml

@@ -16,7 +16,6 @@ en:
     school:
       website: "must be a valid URL"
       school_roll_number: "must be numbers followed by letters (e.g., 01572D)"
-      duplicate_school: "A school with very similar details already exists"
     invitation:
       email_address: "'%<value>s' is invalid"
   activerecord: