I am also facing same issue,
I have two asp.net apps, when i signed in to app 1 it will sign in to both app1 and app2, means app2 wont ask for credentials, but when i click signout from app1 it will signs out only from that app. and in app2 user remains signed in, what is issue? how to sign out form both the apps when signed out from any one app?
for logout/signout i am using this code
var owinContext = this.Request.GetOwinContext();
var authProperties = new AuthenticationProperties()
{
RedirectUri = 'app url'
};
owinContext.Authentication.SignOut(authProperties);
Logout Endpoint is : https://sts.company.com/adfs/ls/?wa=wsignout1.0&wreply=aaplicationurl
Please help me on this.