diff --git a/server/fishtest/rundb.py b/server/fishtest/rundb.py
index b5dbcccb1f..8a1d6975d0 100644
--- a/server/fishtest/rundb.py
+++ b/server/fishtest/rundb.py
@@ -769,27 +769,44 @@ def priority(run):  # lower is better
 
         self.task_runs.sort(key=priority)
 
-        # We go through the list of unfinished runs to see if the worker
+        # get the list of active tasks
+
+        active_tasks = [
+            task for run in self.task_runs for task in run["tasks"] if task["active"]
+        ]
+
+        # We go through the list of active tasks to see if a worker with the same
+        # uuid prefix was already connected.
+
+        my_name = "-".join(worker_name(worker_info).split("-")[0:3])
+        now = datetime.utcnow()
+        for task in active_tasks:
+            task_name = "-".join(worker_name(task["worker_info"]).split("-")[0:3])
+            if my_name == task_name:
+                last_update = (now - task["last_updated"]).seconds
+                # 120 = period of heartbeat in worker.
+                if last_update <= 120:
+                    error = 'Request_task: There is already a worker running with name "{}" which sent an update {} seconds ago'.format(
+                        my_name,
+                        last_update,
+                    )
+                    return {"task_waiting": False, "error": error}
+
+        # We go through the list of active tasks to see if the worker
         # has reached the number of allowed connections from the same ip
         # address.
 
         connections = 0
         connections_limit = self.userdb.get_machine_limit(worker_info["username"])
-        for run in self.task_runs:
-            for task in run["tasks"]:
-                if (
-                    task["active"]
-                    and task["worker_info"]["remote_addr"] == worker_info["remote_addr"]
-                ):
-                    connections += 1
-                    if connections >= connections_limit:
-                        error = (
-                            "Request_task: Machine limit reached for user {}".format(
-                                worker_info["username"]
-                            )
-                        )
-                        print(error, flush=True)
-                        return {"task_waiting": False, "error": error}
+        for task in active_tasks:
+            if task["worker_info"]["remote_addr"] == worker_info["remote_addr"]:
+                connections += 1
+                if connections >= connections_limit:
+                    error = "Request_task: Machine limit reached for user {}".format(
+                        worker_info["username"]
+                    )
+                    print(error, flush=True)
+                    return {"task_waiting": False, "error": error}
 
         # Now go through the sorted list of unfinished runs.
         # We will add a task to the first run that is suitable.