Can we use two $.extend method in a plugin

Can we use two $.extend method in a plugin

Hi...
I'm new to plugin development and i created a new plugin for form validation. I use 
  1. config : {
  2.             //basic configurations
  3.       },
  4. messages : {
  5.             //success error messages
  6.       }
i used  $.extend(this.config,config);  for extending the configuration. Also i need to extend the messages, so that the users can write their custom messages. is there any way to do this??