[keycloak-user] Restricting users by realm

Hi, I have a set of users & 2 realms for 2 different applications. One is my application and other is test vanilla application. These two are using separate realms under single Keycloak server. When a user logged in to my application & when I click login button of vanilla application, it shows that user as logged in. Is this existing scenario in Keyclock? Since user is logged in with different realm, how that user shown as logged in in vanilla app? Is there any way to prevent this? Thanks, Valsaraj Viswanathan