[fix] stop engine from sending duplicated requests

searx/query.py

@@ -113,19 +113,16 @@ class RawTextQuery(object):
                     parse_next = True
                     engine_name = engine_shortcuts[prefix]
                     if engine_name in engines:
-                        for engine_category in engines[engine_name].categories:
-                            self.engines.append({'category': engine_category,
-                                                 'name': engine_name,
-                                                 'from_bang': True})
+                        self.engines.append({'category': 'none',
+                                             'name': engine_name,
+                                             'from_bang': True})
 
                 # check if prefix is equal with engine name
                 elif prefix in engines:
                     parse_next = True
-                    if prefix in engines:
-                        for engine_category in engines[prefix].categories:
-                            self.engines.append({'category': engine_category,
-                                                 'name': prefix,
-                                                 'from_bang': True})
+                    self.engines.append({'category': 'none',
+                                         'name': prefix,
+                                         'from_bang': True})
 
                 # check if prefix is equal with categorie name
                 elif prefix in categories: