ASP.NET forms authentication IIS log file shows POST and GETx2 for a POST request

If a do a login form POST request (with a redirect URL) from my ASP.NET web app client and then look at the IIS logs then I see the POST request but I also see a couple of GETS relating to the redirect. Can anyone explain the sequence of POST-GET-GET shown below - why does the second GET (with the ReturnUrl) exist - does this look correct? All the GETS after the first two make sense to me, but why is /Admin requested twice as shown?

2011-06-06 13:19:20 W3SVC97442007 192.168.1.4 POST /Account/LogOn ReturnUrl=%2fAdmin%2f 80 
2011-06-06 13:19:20 W3SVC97442007 192.168.1.4 GET /Admin/ - 80 
2011-06-06 13:19:20 W3SVC97442007 192.168.1.4 GET /Account/LogOn ReturnUrl=%2fAdmin%2f 80 
2011-06-06 13:19:20 W3SVC97442007 192.168.1.4 GET /Scripts/jquery.form.js - 80 
2011-06-06 13:19:20 W3SVC97442007 192.168.1.4 GET /Content/maintheme.css - 开发者_如何学Go80 
2011-06-06 13:19:20 W3SVC97442007 192.168.1.4 GET /Scripts/jquery-1.6.1.min.js - 80 
2011-06-06 13:19:20 W3SVC97442007 192.168.1.4 GET /Scripts/jquery-ui-1.8.7.min.js - 80 
2011-06-06 13:19:20 W3SVC97442007 192.168.1.4 GET /Scripts/jquery.validate.min.js - 80 
2011-06-06 13:19:20 W3SVC97442007 192.168.1.4 GET /Scripts/json2.js - 80