[Therion] loch with 2 surfaces

[marco corvi]

hi all,

i tried to create a model with two "surfaces":

---------------------------------------------------
source all.th

source
  surface
    cs UTM32
    input surface1.dem
  endsurface
  surface
    cs UTM32
    input surface2.dem
  endsurface
endsource

export model -fmt loch -o cave.lox
export model -fmt dxf -o cave.dxf
------------------------------------------------------

in dxf i got both surfaces, 
in loch only the first.
any reason why ?

thanks, marco