asp.net - HttpContext.Current.User.Identity.Name not right when simultaneous login from 2 machines -

i've got asp.net webserver iis 7.

my authentication code (forms authentication) follows on login page:

            var isauthenticated = membership.validateuser(usernametextbox.text, passwordtextbox.text);             if (isauthenticated)             {                 formsauthentication.redirectfromloginpage(usernametextbox.text, true);             }             else             {                 var customvalidator = new customvalidator();                 customvalidator.isvalid = false;                 customvalidator.errormessage = getlocalresourceobject("loginfailed.errormessage").tostring();                 customvalidator.validationgroup = "allvalidators";                 page.validators.add(customvalidator);             } 

and on page display username:

    if (httpcontext.current.user.identity != null &&         !string.isnullorempty(httpcontext.current.user.identity.name))     {         string authenticatedusername = httpcontext.current.user.identity.name;          return "authenticatedusername=" + authenticatedusername;     }     else     {         return null;     } 

my issue if me , 1 of colleagues login @ same time different login names (and different accounts), accounts set ok (we see different items) 1 of names set other logged in user.

so if login username foo , colleague username bar, both logged in our respective accounts either see user name bar or see username foo on page.

i've seen other accounts of strange behaviour of asp.net authentication , claimed fixed disabling output cache feature. didn't work me.

any appreciated, i've got no idea how track issue.

in end issue code. wanted disable caching page , used following

<%@ outputcache duration="1" nostore="true" varybyparam="none" %> 

which seemed work , correct. wasn't complete though , full version

<%@ outputcache duration="1" nostore="true" location="none" varybyparam="none" %> 

which works.

a posteriori it's obvious waht happened. although client won't store page, asp 1 second if location isn't set none.

the documentation on msdn confusing form me topic.