remove duplicate array keys

Name
utf8.php

Location
\system\helper\utf8.php

Problem synopsis:
Duplicate array key (at line 189)
Duplicate array key (at line 190)
Duplicate array key (at line 249)
Duplicate array key (at line 263)
Duplicate array key (at line 268)
Duplicate array key (at line 269)
Duplicate array key (at line 425)
Duplicate array key (at line 426)
Duplicate array key (at line 485)
Duplicate array key (at line 499)
Duplicate array key (at line 504)
Duplicate array key (at line 505)