Handling Multiple Requests

Hi,

I am facing a problem in restricting the user from sending the second request. The scenario is:
I have a form (non-modal pop up) which accepts inputs from the user, user clicks on save once he finishes entering the data. Meantime when the FirstRequest is being processed, user does a right click refresh on the same form, this refresh sends one more request (SecondRequest) to the server. As a result i loose the handle over the FirstRequest and user is not confirmed whether the save is completed successfully.

Please reply whether handling this @ Client Side or handling it @ Server side will be beneficial.
Note: I cannot disable right click refresh on the form.