Is my cache being shared by the pages able to leave it per session?

Question

Good morning, you guys, So, I created a class to handle cache, but open the site in the same browser but with different users, one takes the cache from the other. how can I restrict by "session" that? Thank you !

Methods:

    public T GetKeyValue<T>(string key)
    {
        var cache = HttpContext.Current.Cache[key];
        if (cache != null)
            return (T)cache;

        return default(T);
    }

    public void SetKeyValue<T>(T obj, string key)
    {
        if (string.IsNullOrEmpty(key) || obj == null)
            return;

        HttpRuntime.Cache.Insert(key, obj,
                        null,
                        DateTime.Now.AddHours(1),
                        Cache.NoSlidingExpiration 
                        );
    }

UPDATE

When opening another tab, this method overwrites the "user" so all open sites take colors, styles, user settings you have... my doubt is, how to do this cache per user in a correct way, clean etc. because I concatenei but still sometimes breaks something

   public void Authenticate(string user)
    {
        if (CanAuthenticated(user))
        {
            this.User = user;
            this.Password = "password";
            var villaUser = this.SPAccessLogin.LogIn();
            this.VillaSiteUser = villaUser;
            this.IsAuthenticated = true;
        }
    }