Added process ID to machine name.

src/Orchard/Environment/MachineNameProvider.cs

@@ -1,7 +1,12 @@
-namespace Orchard.Environment {
+using System;
+using System.Diagnostics;
+
+namespace Orchard.Environment {
     public class MachineNameProvider : IMachineNameProvider {
         public string GetMachineName() {
-            return System.Environment.MachineName;
+            // Add process ID to machine name because multiple web servers can
+            // be running on the same physical machine.
+            return String.Format("{0}:{1}", System.Environment.MachineName, Process.GetCurrentProcess().Id);
         }
     }
 }