Rail duplication!

Hello! I found this bug while making a "rollercoaster", what this allows you to do is duplicate rails.

Step one, you'll need a sticky piston, a slime block, a stone block, a mine cart, 1 activator rail and a few bits of red stone.

Find some flat land and place the piston facing up, then place the slime block above (when powered it pushes the slime block up) put a stone block any side of the piston but it must be touching, then put the activator rail on the stone and place your minecart. BOOM out pop TWO activator tracks from your first one.

If that didn't work you need some red stone coming from the stone block into the piston and then re-do the last few steps.

If needed I can supply a video or picture.