--- broker.original
+++ M05-collision
@@ -6436,8 +6436,6 @@
         // Preflight all collisions/missing threads before open creates or send writes anything.
         const threads = members.map((instance) => {
           const t = this.#store.get('SELECT * FROM threads WHERE project=? AND name=?', project, instance);
-          if (t && (t.instance !== instance || t.owner !== owner))
-            fail(opening ? 'room-thread-name-taken' : 'room-not-open');
           if (!t && !opening) fail('room-not-open');
           return t ?? { instance, name: instance };
         });