Function xxxx already exists, add ! to replace it

here is my .vimrc

1 execute pathogen#infect()
2 execute pathogen#helptags()
3 syntax on
4 filetype plugin indent on
5
6 let g:pydiction_location = '/home/guest/.vim/bundle/dict/pydiction/complete-dict'
7 let g:pydiction_menu_height = 10
8
9 au FileType python call PyFun()
10 function PyFun()
11 set tags+=/home/guest/.vim/tags/python.tag
12 autocmd FileType python set omnifunc=pythoncomplete#Complete
13 endfunction
14
15 au FileType c call CFun()
16 function CFun()
17 set tags+=/home/guest/.vim/tags/c.tag
18 autocmd FileType c set omnifunc=ccomplete#Complete
19 endfunction
20
21 au FileType php call PhpFun()
22 function PhpFun()
23 set dictionary-=$HOME/.vim/bundle/dict/vim-php-dictionariy/dict/PHP.dict dictionary+=$HOME/.vim/bundle/dict/vim-php-dictionary/dict/PHP.dict
24 autocmd FileType php set omnifunc=phpcomplete#Complete
25 endfunction
26
27 let g:tern_show_signature_in_pum = 1


:source .vimrc

result in some error info

Error detected while processing /home/guest/.vimrc:
line 13:
E122: Function PyFun already exists, add ! to replace it
line 19:
E122: Function CFun already exists, add ! to replace it
line 25:
E122: Function PhpFun already exists, add ! to replace it
Press ENTER or type command to continue

Are there something wrong to fix?

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