When lazy loading with multiple commands only the triggerring command is deleted.

[igrekster]

It would seem that vim-plug only deletes the triggering command before loading the script, leaving the other triggers "active". This may cause issues for plugins that are not reload-friendly:

:Plug 'sjbach/lusty', { 'on' : ['LustyJuggler', 'LustyBufferExplorer', 'LustyFilesystemExplorerFromHere'] }<CR>
:LustyJuggler<CR>
Error detected while processing plugged/lusty/plugin/lusty-explorer.vim:
line  251:
E174: Command already exists: add ! to replace it
line  253:
E174: Command already exists: add ! to replace it

[junegunn]

I see. It's unfortunate that the plugin does not use command! :(
I'll see what I can do, thanks for the report.

[junegunn]

Fixed it. Let me know if you still see the problem.

[igrekster]

Works like a charm now, thanks!