diff --git a/LuaLibs/BeamExec.lua b/LuaLibs/BeamExec.lua
index a1732f6..d003a51 100644
--- a/LuaLibs/BeamExec.lua
+++ b/LuaLibs/BeamExec.lua
@@ -1432,18 +1432,17 @@ local function FindMirrorFeature( vProc, Proc, sFeatureType, dHBeam)
    -- se mortasa a coda di rondine
    if sFeatureType == 'DtMortise' then
       Proc.Side = EgtGetInfo( Proc.Id, 'SIDE', 'i')
-      if Proc.Side == 1 or Proc.Side == 3 then
          for i = 1, #vProc do
             local ProcMirror = vProc[i]
             if DtMortise.SideIdentify(ProcMirror) then
                ProcMirror.Side = EgtGetInfo( ProcMirror.Id, 'SIDE', 'i')
-               if ( Proc.Side == 1 and ProcMirror.Side == 3) or ( Proc.Side == 3 and ProcMirror.Side == 1) then
+               if ( Proc.Side == 1 and ProcMirror.Side == 3) or ( Proc.Side == 3 and ProcMirror.Side == 1) or
+                  ( Proc.Side == 2 and ProcMirror.Side == 4) or ( Proc.Side == 4 and ProcMirror.Side == 2) then
                   local bIsMirror = CheckMirrorDtMortise( Proc, ProcMirror, dHBeam)
                   if bIsMirror then nProcMirror = i end
                end
             end
          end
-      end
    end
    -- se foratura (da implementare)
    return nProcMirror