diff --git a/LuaLibs/BeamExec.lua b/LuaLibs/BeamExec.lua
index 94275a7..e8e7b81 100644
--- a/LuaLibs/BeamExec.lua
+++ b/LuaLibs/BeamExec.lua
@@ -1991,6 +1991,11 @@ local function AreDrillingsMirrored( Proc, ProcMirror, b3Raw)
       end
    end
 
+   -- fori della stessa profondità
+   if abs( Proc.Len - ProcMirror.Len) > 10 * GEO.EPS_SMALL then
+      return false
+   end
+
    return true
 end