diff --git a/Main.lua b/Main.lua
index 06cffce..5d489ce 100644
--- a/Main.lua
+++ b/Main.lua
@@ -1090,6 +1090,12 @@ function ExtendedEstimate(readBatch)
 end
 --
 
+-- verifico che non ci siano istanze gia' in corso
+if not EgtCreateMutex('Global\\MainNKCLuaScript') then
+   EgtOutLog( 'Impossible starting script! Script already in execution!')
+   EgtOutBox( 'Script already running! Impossible running another instance at the same time!!', 'Error' , 'ERROR', 'OK')
+   EgtCloseExe()
+end
 -- ciclo principale
 while true do
    EgtNewFile()
@@ -1115,5 +1121,5 @@ while true do
          end
       end
    end
-
 end
+EgtReleaseMutex()
diff --git a/NestingLib.lua b/NestingLib.lua
index f58ce0c..2f6326c 100644
--- a/NestingLib.lua
+++ b/NestingLib.lua
@@ -2703,8 +2703,8 @@ function NestingLib.ManageMachine(CurrIsOffline)
       table.insert(OutlineMachining, 2, Config.NWOutlineMachTools)
       table.insert(HoleMachining, 2, Config.NWHoleMachTools)
       table.insert(RampMachining, 2, Config.NWRampMachTools[1])
-      table.insert(CountersinkMachining, 2, Config.NWCountersinkMachTools)
-      table.insert(OutsideChamferMachining, 2, Config.MXOutsideChamferMachTools)
+      table.insert(CountersinkMachining, 2, Config.NWCountersinkMachTools[1])
+      table.insert(OutsideChamferMachining, 2, Config.MXOutsideChamferMachTools[1])
       table.insert(InsideChamferMachining, 2, Config.NWInsideChamferMachTools[1])
       Pocketing =  Config.NWPocketingTools
       IsOffline = true