Asking for confirmartion on node creation
@AgA: "I want ask for confirmation if a duplicate node is getting created. But how do I do it?"

The way you do it is to validate any new node added by a user against existing nodes.

Towards this end, hook_node_validate() is your friend. :-) You'd make a module that implements hook_node_validate(), and within that function do a query using the data the user input. If you find similar nodes that already exist, you can form_set_error() an error message. Click through to the API site and there's even some sample code.