http://www.w3.org/TR/2011/WD-workers-20110310/#shared-workers-and-the-sharedworker-interface

Step 7.5 is
"If name is not the empty string and there exists a SharedWorkerGlobalScope object whose closing flag is false, whose name attribute is exactly equal to name, and whose location attribute represents an absolute URL with the same origin as scriptURL, then let worker global scope be that SharedWorkerGlobalScope object."

7.6. is 
"Otherwise, if name is the empty string and there exists a SharedWorkerGlobalScope object whose closing flag is false, and whose location attribute represents an absolute URL that is exactly equal to scriptURL, then let worker global scope be that SharedWorkerGlobalScope object."

7.8 is
"Create a new SharedWorkerGlobalScope object. Let worker global scope be this new object."


Example web page is
<script>
  var sw1 = new SharedWorker("worker.js", "1");
  sw1.port.onmessage = function(e) { alert("sw1: " + e.data); }
  var sw2 = new SharedWorker("worker.js", "2");
  sw2.port.onmessage = function(e) { alert("sw2: " + e.data); }
  var sw3 = new SharedWorker("worker.js");
  sw3.port.onmessage = function(e) { alert("sw3: " + e.data); }
</script>

and worker 
onconnect = function(e) {
  var port = e.ports[0];
  port.postMessage("worker name: " + name);
}

Since sw1 and sw2 have different names, they get separate workers per 7.5 and 7.8.

Because sw3 doesn't have name, 7.6 applies. Both sw1 and sw2 fulfill the criteria of a worker
whose closing flag is false and location attribute is the same as sw3's location, so sw3 is
connected randomly to either one of those workers.
That is very strange.


Opera seems to implement what the spec says, Chrome creates a new worker for sw3.