Refracting refractions?

Would it be possible to have refractive materials refract other refractive materials that are behind them? I know performance would be horrible if the refraction buffer is built too many times, but stuff like this just looks silly.

img212.imageshack.us/img212/3502/screenshot001000040fr.png

I was thinking that if you built a back-to-front BSP tree for the refraction objects that overlap each other, you'd beable to copy them to the refraction buffer after each(group) is rendered. I realise this might kill performance with too many overlapped objects, so one could limit the amout of calls to copyBBToSfxBuff to say 3 or 4 total. I'm wondering if someone that knows more about TSE rendering could tell me if this is a bad idea or not.

Here's some pseudo-code to give a better idea of what I'm thinking.

void SceneState::renderCurrentImages()
{
...........

   // Render refraction images
   //-----------------------------
   if( mRefractionImages.size() &&
       !gClientSceneGraph->isReflectPass() )
   {
      // set ortho projection matrix
      MatrixF proj = GFX->getProjectionMatrix();
      MatrixF newMat(true);
      GFX->setProjectionMatrix( newMat );
      GFX->pushWorldMatrix();
      GFX->setWorldMatrix( newMat );

      // copy sfx back buffer out to tex
      GFX->copyBBToSfxBuff();

      // restore projection matrix
      GFX->setProjectionMatrix( proj );
      GFX->popWorldMatrix();

      buildRefractiveBSP(); // Only adds overlapped refractive images to the tree(and removes them from mRefractionImages?)

      // render overlapped refraction surfaces
      for (i = 0; i < mMultipleRefractionImages.size(); i++)
      {
         for(U32 s; s < mMultipleRefractionImages[i].images.size(); s++) {
            renderImage( this,  mMultipleRefractionImages[i].images[s]);
         }

         set projection and world matrix
         copyBBToSfxBuff();
         restore projection matrix
      }

      // render refraction surfaces
      for (i = 0; i < mRefractionImages.size(); i++)
      {
         renderImage( this, mRefractionImages[i] );
      }
   }

...........
}