handling multiple requests using Session.

Hello,  I am new to ASP.Net MVC and am using MVC 5 for my project. I came across a problem of handling multiple requests in the application.  I need to enter and ID and based on that I would get zip file for the updated information. For single request it was working fine. When I tried opening two tabs and entering two different ID then I got same zip file for both IDs. Can anyone please suggest me any approach.