Duplicate Movie Clips

I am trying to create something in which a movieclip tweens across the screen horizontally, once spacebar is clicked. In a certain interval i want the same movieclip to be duplicated, but on a different position on the yaxis, and then to tween across. I want this to happen for upwards of 150 or so times.
Thanks.

Make the tween inside the movieclip (make another clip into this one). Then just duplicate the movieclip using duplicateMovieClip(mcname, newname, depth) and set another _y position to it (newname._y = somenumber). Hope that helps