Persistent security across two IIS servers.

Hi,

We're having a problem that the developer has suggested a solution to and we're not quite sure that's the right way of doing it and would like some input as to how we could resolve the issue.

So here's the synopsis of what we're doing currently:

We have a website that lives on one server.  Customers access it with their username and password.

This website at some point calls a second website (different IIS server) and performs some action(s).  

Then the second website returns the user to the first website for finalizing the business they were doing.

We have no choice in the multiple IIS servers.

We would like to keep customers who bookmark the link to the second server from re-accessing that URL after they close the browser and/or a time-out.  The developer suggested using Session ID's but I'm under the impression that the session ID would not be passed to the second server.  In addition the developer wants to create a SQL entry with a time-stamp of when this URL expires, but honestly I think we rather just have it expire when the client closes the browser.

So, to the question I think I'm asking.

Is there a cleaver way of making a URL ONLY work once.   I see ways of passing a UniqueIdentifier or something but is that the way to go?

We can't trust users pressing a "Logout" button, so it somehow has to be done by the site.

It's written in C# with visual studio 2013.

Thank you
~j