Why is it that

Why is it that…


onClipEvent(mouseDown){
     x++
     trace(x);
};

has an output of:
1
2
3
4
etc.
based on the number of times you click the mouse.
However…


onClipEvent(mouseDown){
     x++
     this.duplicateMovieClip("newMC"+x,x)
     trace(x)
}

has an output of:
1
2
1
3
1
4
1
1
2
5

after 5 clicks. Why is that?