diff --git a/secert-hitler/src/controller/state/mockroom.rs b/secert-hitler/src/controller/state/mockroom.rs
index cd57dc5..82f08fa 100644
--- a/secert-hitler/src/controller/state/mockroom.rs
+++ b/secert-hitler/src/controller/state/mockroom.rs
@@ -3,13 +3,14 @@ use super::event::Event;
 
 use rand::{self, Rng};
 use rand::distributions::Alphanumeric;
-use crossbeam_channel::{unbounded, Receiver, Sender};
+use crossbeam_channel::{unbounded, Sender, Receiver};
 
 #[derive(Clone, Debug)]
 pub struct MockRoom {
    last: String,
    room_id: String,
-   events: Vec<Event>,
+   events_s: Sender<Vec<Event>>,
+   events_r: Receiver<Vec<Event>>,
 }
 
 impl MockRoom {
@@ -18,10 +19,13 @@ impl MockRoom {
    }
 
    pub fn join(room_id: String) -> MockRoom {
+      let (s, r) = unbounded();
+      s.send(vec![]).ok().unwrap();
       MockRoom {
          last: "".to_string(),
          room_id: room_id,
-         events: vec![],
+         events_s: s,
+         events_r: r,
       }
    }
 
@@ -34,7 +38,8 @@ impl Room for MockRoom {
    fn sync(&mut self) -> Vec<Event> {
       let mut unseen: Vec<Event> = vec![];
       let mut last = self.last.clone();
-      for e in &self.events {
+      let events = self.events_r.recv().ok().unwrap();
+      for e in &events {
          if e.next == self.last {
             unseen.clear();
          } else {
@@ -42,6 +47,7 @@ impl Room for MockRoom {
             last = e.next.clone();
          }
       }
+      self.events_s.send(events).ok().unwrap();
       self.last = last;
       return unseen;
    }
@@ -52,7 +58,9 @@ impl Room for MockRoom {
          next: rands(),
          body: message,
       };
-      self.events.push(e);
+      let mut events = self.events_r.recv().ok().unwrap();
+      events.push(e);
+      self.events_s.send(events).ok().unwrap();
       Ok("ok")
    }
 
@@ -63,7 +71,7 @@ impl Room for MockRoom {
 
 impl Drop for MockRoom {
    fn drop(&mut self) {
-      println!("not impl");
+      println!("MockRoom::drop not impl");
    }
 }
 
@@ -84,14 +92,15 @@ mod tests {
    fn _dummy() -> MockRoom {
       let mut r = MockRoom::create();
       r.last = "1".to_string();
-      r.events = vec![];
+      let mut events = r.events_r.recv().ok().unwrap();
       for i in 0..5 {
-         r.events.push(Event{
+         events.push(Event{
             sender: i.to_string(), 
             next: i.to_string(), 
             body: i.to_string(),
          });
       }
+      r.events_s.send(events).ok().unwrap();
       r
    }
 
diff --git a/secert-hitler/src/controller/state/mockrooms.rs b/secert-hitler/src/controller/state/mockrooms.rs
index 963aa5f..9b1f042 100644
--- a/secert-hitler/src/controller/state/mockrooms.rs
+++ b/secert-hitler/src/controller/state/mockrooms.rs
@@ -86,4 +86,38 @@ mod tests {
       assert!(r.is_ok());
       assert!(r.ok().unwrap().room_id() == "0");
    }
+
+   #[test]
+   fn join_clobber() {
+      let mrs = _dummy();
+      let mut a = mrs.join("0".to_string()).ok().unwrap();
+      let mut b = mrs.join("0".to_string()).ok().unwrap();
+      assert!(a.room_id() == b.room_id());
+      assert!(a.sync().len() == b.sync().len());
+      assert!(a.sync().len() == b.sync().len());
+      assert!(a.sync().len() == 0);
+      assert!(b.sync().len() == 0);
+      assert!(a.send("from a".to_string()).is_ok());
+      assert!(a.sync().len() == 1);
+      assert!(b.sync().len() == 1);
+      assert!(b.send("from b".to_string()).is_ok());
+      assert!(b.send("from b".to_string()).is_ok());
+      assert!(a.sync().len() == 2);
+      assert!(b.sync().len() == 2);
+      assert!(a.send("from a".to_string()).is_ok());
+      assert!(b.send("from b".to_string()).is_ok());
+      assert!(a.send("from a".to_string()).is_ok());
+      assert!(a.sync().len() == 3);
+      assert!(b.sync().len() == 3);
+      assert!(a.send("from a".to_string()).is_ok());
+      assert!(b.send("from b".to_string()).is_ok());
+      let a = a.sync();
+      let b = b.sync();
+      assert!(a.len() == 2);
+      assert!(b.len() == 2);
+      assert!(a[0].body == "from a");
+      assert!(b[0].body == "from a");
+      assert!(a[1].body == "from b");
+      assert!(b[1].body == "from b");
+   }
 }