When use 'lazy' option get waring message 'plugin name is already defined.'

[hare001]

Problems summary

When I use call dein#add('suan/vim-instant-markdown', {'lazy': 1, 'on_ft': 'markdown'}) or call dein#config('vim-instant-markdown', {'lazy': 1, 'on_ft': 'markdown'}), I got a warning message when I save init.vim file.like this:[dein] Plugin name "vim-instant-markdown" is already defined.

Expected

no warning message when I save init.vim file.

Environment Information (Required!)

• dein.vim version(SHA1):c6ddf04183606413870a0f8a86f61f8d58f85982

• OS:macOS Catalina version 10.15.7

• Vim/neovim version:NVIM v0.5.0-nightly

Provide a minimal .vimrc with less than 50 lines (Required!)

" Your minimal .vimrc
let s:dein_path = '~/.config/nvim/dein'
let &runtimepath = &runtimepath.','.s:dein_path.'/repos/github.com/Shougo/dein.vim'
call dein#begin(s:dein_path)
call dein#add('suan/vim-instant-markdown', {'lazy': 1, 'on_ft': 'markdown'})
"call dein#add('suan/vim-instant-markdown')
"call dein#config('vim-instant-markdown', {
            "\ 'lazy': 1, 'on_ft': 'markdown',
            "\ })
call dein#end()

if dein#check_install()
    call dein#install()
endif
autocmd! BufNewFile $MYVIMRC source %

The reproduce ways from Vim starting (Required!)

1. :call dein#install() to install plugins
2. :w to save the init.vim file
3. if the second step doesn't show warning message, use :w to save twice

Screen shot (if possible)

Upload the log messages by :redir and :message (if errored)

"init.vim" 483L, 11854C 已写入
[dein] Plugin name "vim-instant-markdown" is already defined.
[dein] Plugin name "vim-markdown-toc" is already defined.

[Shougo]

Closing. Because you don't have uploaded reproduce-able vimrc.

Why? It is not included BufWritePost autocmd in the vimrc.

[Shougo]

set runtimepath^=~/work/dein.vim
if dein#load_state('~/work/test')
  call dein#begin('~/work/test')

  " markdown
  call dein#add('suan/vim-instant-markdown')
  "call dein#config('vim-instant-markdown', {
        "\ 'lazy': 1, 'on_ft': 'markdown',
        "\ })
  call dein#add('mzlogin/vim-markdown-toc')
  "call dein#config('vim-markdown-toc', {
        "\ 'lazy': 1, 'on_ft': 'markdown',
        "\ })

  call dein#end()
  call dein#save_state()
endif

autocmd! bufwritepost $MYVIMRC source %

It works for me.

[Shougo]

Reproduced.