Disallow reattaching COM events

Author: mansellan

Rubberduck.VBEEditor/SafeComWrappers/SafeRedirectedEventedComWrapper.cs

@@ -35,17 +35,20 @@ protected void AttachEvents(IEventSource<TEventSource> eventSource, TEventInterf
             if (eventSource == null || eventSink == null)
             {
                 return;
-            }
-
-            // Only one event source and one event sink supported at any given time
-            DetachEvents();
+            }            
 
             lock (_lock)
             {
                 if (IsWrappingNullReference)
                 {
                     return;
                 }
+                
+                // Check that events not already attached
+                if (_eventSource != null || _eventSink != null)
+                {                   
+                    return;
+                }
 
                 _eventSource = eventSource.EventSource;
                 _eventSink = eventSink;